Direct Black 21
Name:C.I.Direct Black 21,C.I.31580
Molecular Structure: trisazo class
Molecular Formula:C35H26N9Na3O9S2
Molecular Weight: 849.74
CAS Registry Number:6428-51-9
Manufacturing Methods : N-(4-aminophenyl)acetamide diazo, in alkaline conditions and 6-Amino-4-hydroxynaphthalene-2-sulfonic acid, hydrolysis amido group, and a double nitride, first with 8-Aminonaphthalene-2-sulfonic acid coupling, again with N-(2-methyl-5-aminophenyl)glycine coupling.
Properties and Applications: black. Soluble in water for blue-ray black. The strong sulfuric acid in dark green. The dye solution to join hydrochloric acid have blue-black precipitation; Add sodium hydroxide colored light red.
Standard | Acid Resistance | Alkali Resistance | Light Fastness | Soaping | Water | ||
Fading | Stain | Fading | Stain | ||||
ISO | 4 | 2 | 2-3 | 2-3 | 1-2 |
List of Suppliers:
Direct Resist Black M( Industria Chimica Dott )