Method of dyeing nylon to produce colorfast fiber which resists further dyeing

Abstract

A method of dyeing nylon, particularly cationic dyeable Type 6 and 66 nylon and light dyeable Type 66 nylon, so that the dyed fiber will resist taking on further dye and will have a high degree of wash and bleed fastness when the dyed fiber is subjected to a further high temperature aqueous dye bath. The method includes providing a bifunctional dye solution having a very low pH, i.e. no higher than 1.5. The dye is applied to the fiber with a degree of wet pick-up exceeding 100% by weight of the fiber. The fiber is then steamed, washed, and dried, and contacted by an alkaline solution, such as a trisodium phosphate solution. Thereafter, the fiber is autoclaved. Such a dyed nylon fiber can be combined with an undyed nylon fiber to produce a textile product. When such a product is subjected to a dyeing operation, to provide the undyed nylon with a color different from the color of the previously-dyed fiber, the previously-dyed fiber will not bleed or wash out, and will resist taking on the dye being used to color the undyed nylon.

Dependencies are inferred from the claim text.