Direct Black 19

 Colour Fastness Test

Direct Black 19 (Direct Fast Black G) alias direct light fast black, direct fast black G. Appearance is generally black powder. Water soluble, soluble in water, greenish black, slightly soluble in alcohol and acetone. Dyes in concentrated sulfuric acid It is greenish black and black. It is reddish black after dilution. It is dark brown in concentrated nitric acid. Its aqueous solution is added with 10% sulfuric acid to become reddish, and concentrated sodium hydroxide is greenish blue. In case of copper ion light, it is slightly green. The iron ion shade changes slightly.

Used in viscose of dyeing and printing. In the cotton knitwear, blankets, flannelette, silk, viscose, silk that the fabric, wool/viscose fiber blend fabrics can be used. Can also be used in leather, paper and electrochemical aluminum color.

Use condition:

1. Direct Fast Black G dyed cotton or viscose fiber has green light black. Poor transferability, slow temperature rise and dyeing should be used to control dyeing to obtain uniform color. Good dyeing rate. The stage dyeing solution should be naturally cooled to 80 ° C, which is beneficial to the dye exhaustion. After dyeing, the color light is unchanged after finishing with urea-formaldehyde resin, and the wet processing fastness can also be improved.

2. Direct Black 19 is also used for dyeing and printing of silk, wool and cotton or viscose fiber interlaced or blended fabrics. When cotton, viscose and other fibers are dyed in the same bath, vinylon, silk and wool are colored. Lighter than cotton and viscose, nylon, polyester, acrylic, and diacetate are brownish yellow.

3. It can be mixed with disperse dyes at high temperature to dye polyester blended fabric. The dye bath is heated to 120 ° C under neutral conditions, or loaded with boiling dye. After the dye is dyed with polyester, the dye is cooled. Continue to dye for half an hour, so that the cellulose fibers are fully colored, causing the dye to be exhausted and the color light to change slightly.

4. Direct Black 19 can be used for continuous padding of cotton, steaming and drying at 100~103 °C for 1~3min.

5. It can be used for direct printing of cotton or viscose fabric, plus urea and disodium hydrogen phosphate to prepare color paste.

6. Direct Fast Black G is one of the main black direct dyes. It is widely used in dyeing and printing of viscose fabrics, mainly used for dyeing black. It is also used to form various kinds with brown dyes. Coffee of different depths, a small amount is used to adjust the color of light to increase the chromatogram. It is also used in the dyeing of cotton knitwear, carpet, flannel, etc. It can also be used for dyeing silk and viscose fiber and silk fabric, wool. It is blended with the viscose fiber on the black. It is also used for the dyeing of silk fabrics. The whitening performance is good, but the dark color is slightly worse.

Precautions

Direct Black 19 is not a banned dye. However, it should be noted that when the dye is synthesized, the diazonium ion of the p-nitroaniline is cleaved off under a basic condition, and then the self-coupling is 4,4'-dinitrobiphenyl. Finally, benzidine is produced.