Dyeing of Modified Polypropylene: Cationic Dyes on Chlorinated Polypropylene

Polypropylene fiber was chlorinated by the action of sodium hypochlorite under specific conditions. On chlorination, the moisture content of the fiber increased, but there was no effect on the fiber's mechanical properties.

On chlorination, marked affinity was created in the fiber for cationic dyes from alkaline medium. Eight different cationic dyes were used on the chlorinated product under different dye bath pH conditions. Dyeings tended to show that the mechanism of application of cationic dyes on chlorinated polypropylene was a reactive type, i.e., through the formation of a covalent bond between the fiber and the dye.

Of the eight cationic dyes, seven possessed poor to moderate light fastness, only Methylene Blue (CI Basic Blue 9) gave very good light fastness. In all the eight dyeings, other fastness properties such as fastness to washing, bleach, sea-water, and soda-boil were good. All the eight dyeings were after-treated with iodine which increased light fastness. Of the eight dyes, four produced photodegrading action on the fiber and four afforded photoprotection. Methylene Blue gave very good photoprotective action to the chlorinated polypropylene fiber.