Theory of Dyeing Polyester and Polyacrylic Fibers1

Abstract

These two fiber classes are similar in that both are dyed by disperse-type dyes; however, polyacrylic fibers can be dyed with anionic dyes if positive sites are provided. This can be done, for example, by using fiber containing ammonium groups. Alterna tively, positive sites in the form of bound cuprous ions can be produced by treatment of the fiber with cuprous salts. In either case, ion exchange occurs in which colorless anions and dye amons compete for positive sites in the fiber. In contrast, disperse dyes, which are used on all common fibers except cellulose and wool, require no specific dyeing sites. In polyethylene terephthalate, the dyeing reac tion behaves like a simple solution in the tiber, with dipole interactions and dispersion forces probably very important. The rate of dyeing of polyethylene terephthalate tends to be inconveniently slow, and organic compounds called carriers are used frequently to increase the rate. They are effective by mcreasing the diffusion rate of dye through the fiber.