C.I.Direct Red 31
Molecular Structure: Double azo class
Molecular Formula: C32H21N5Na2O8S2
Molecular Weight: 713.65
CAS Registry Number: 5001-72-9
Properties and Applications: colourful red blue light. Red brown powder. Soluble in water for product red solution, the solubility of 45 g/L (80 ℃), also can dissolve in fiber element solution, slightly soluble in alcohol for red orange, insoluble in other organic solvents. The strong sulfuric acid in orange to red light for brown, diluted dark blue light red precipitate generated; In nitric acid solution for orange brown, precipitation. The dye solution to generate strong hydrochloric acid purplish red precipitate; Add thick sodium hydroxide solution for orange brown. Copper ions in dyeing dim light; Iron ion in micro have change. Mainly used in viscose, such as cotton, silk, polyamide fiber cellulose fiber and viscose/silk blended fabric dyeing, can be used for pulp shading.
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