Dyeing Processes on Cellulosic Fibers

The use of naphthols and bases in solution was introduced in the 1970s. These formulations are safer and simpler to apply. Diazotization of the liquid bases generally does not require the addition of ice. 

After development, the textile is rinsed and subjected to careful afterwash in which excess dye lake is removed from the fiber surface. Otherwise, it severely impairs the rubbing-fastness of the dyeing. In addition, through the change in pigment crystal structure occurring during aftertreatment, a stable final shade is achieved with enhanced fastness.  

Naphtol AS combinations that can be used at low temperature are suitable for dyeing cellulose fiber materials that are partially coated with wax batik). After dyeing the wax is washed out by boiling. 

The use of Naphtol AS dyes for the production of denim articles is of some interest. The cotton warps are simultaneously sized and padded with a coupling component. After weaving the fabric is developed with a Yast salt , i.e. a diazotized base and subjected to the usual aftertreatment. 

3 Printing with Azo (Naphtol AS) Dyes on Cellulosic F ibers 

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