Direct Black 19

Using m-phenylenediamine, p-nitroaniline, and H acid as raw materials, first diazotize p-nitroaniline, and then couple with H acid for the first time in a weak acid medium. Then couple with H acid for the second time under weak alkaline conditions. Then use alkali sulfide to reduce the nitro group, diazotize, and couple with m-phenylenediamine for the third time to obtain the product. After salting out, filtering, drying and crushing, the finished product is obtained. . Add 400L of water, 650kg of hydrochloric acid (30%), and 276kg of p-nitroaniline (100%) to the diazonium pot, raise the temperature to 80℃, stir to dissolve it, then add 800-1000kg of ice, and cool to 1-2℃. Quickly add 140.8kg sodium nitrite (100%) under the liquid, maintain the reaction temperature ≤16℃, react for 40min, until the solution is transparent. Take 325kg (100%) of H acid and 450kg of water to make a slurry, then quickly add it to the above diazonium solution, maintain the reaction temperature ≤18℃, and maintain the reaction for about 40-50 minutes. Then add ice to cool to 8-10℃, quickly add 300-320kg of soda ash powder (adding in about 10min), maintain ≤20℃ to complete the second coupling reaction. Take 235kg of sodium sulfide and 1000kg of water to dissolve it by heating, then cool it to 50°C naturally, add it to the above coupling solution, heat up to 35°C, and react for 1-2h. After the reaction is over, add 1000kg hydrochloric acid (30%) for acid precipitation, and the addition is completed in about 1 hour. Then the temperature was raised to 60°C to catch the sulfur dioxide for 4h and filtered. Take filter cake, 1000L of water, 58kg of soda ash, and make a slurry. The temperature is raised to 60°C and filtered with suction. Add 127kg of sodium nitrite (100%) to the filtrate. Add 550kg of hydrochloric acid (30%), ice and water to another diazonium pot, cool to ≤18℃, add the above-mentioned sodium nitrite-containing filtrate, add it in about 1h, continue the reaction for 3h, take potassium iodide test paper to measure the end point. Then add ice, cool to 5-6°C, add soda ash powder, adjust the pH to 6.5, add 110kg m-phenylenediamine (100%), and react at 20°C for 2h. After filtering, add 1500L of water and 20kg of soda ash to the filter cake, beating and drying to obtain about 900kg of dye.

Direct light fast black G is one of the main black dye varieties. Mainly used for dyeing and direct printing of cotton, viscose fiber, cotton, viscose fiber interwoven with silk, wool, blended fabrics. It is mainly dyed black, and gray and black are generally used for printing. It can also be combined with brown dyes to make coffee and other colors of various depths. A small amount is used to adjust the light to increase the color spectrum. When dyeing wool viscose fiber blended fabric, it can be dyed in the same bath with neutral black BRL to obtain uniform color. It can also dye polyester-viscose blended fabric in the same bath with disperse dyes. The dyeing rate is good and the dye transferability is slightly worse. After dyeing, it can be treated with fixing agent Y and fixing agent M, but the color is slightly green. Finishing with urea-formaldehyde resin can improve the color fastness without changing the color.