Direct dyes cationic fixing agents

A single-bath method can be used if desired. The dyes are dissolved separately and added to the dyebath which already contains an ethylene oxide condensate which acts as an anti-precipitant. The dyebath is adjusted to pH 5 to 5-5 with acetic acid and sodium acetate and the goods are entered at 40 to 45°C (104 to 113°F). A period of 45 minutes is taken to raise the temperature to the boil, at which it is maintained for one hour. Alternatively, the acrylic fibre may be dyed first and then the same liquor is neutralized and the cellulosic fibre is dyed. Application of a cationic fixing agent improves wet fastness of direct dyes but copper after-treatment should be avoided because this can have an adverse effect on the light fastness of the cationic dye. Very good fastness is obtained if, after the acrylic component has been dyed, the cellulosic fibre is brought to shade with vat dyes. 

Because many direct dyes do not have good washfastness and lightfastness, their dyeings on cotton are often treated with a chemical agent, in what is commonly known as an aftertreatment process. The most widely used aftertreatment methods involve (1) cationic fixatives, (2) copper sulfate, or (3) diazotiza-tion and coupling reactions. The first and third methods are designed to enhance wash-... 

Sanfix. [Sanyo Chem. hidustries] Cationic resins fixing agent fm direct and reactive dyes. 

Chem. Descrip. Polyamine condensate Ionic Nature Cationic Uses Fixing agent for direct dyes Properties Liq. 30% cone. 

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