CONTROLLING NYLON DYEING BY DYE AND CHEMICAL METERING

Closed-loop control of the dosing of dyes and chemicals is used to obt ain an on-tone build-up of shade in dyeing polyamide fibers with a bin ary mixture of monosulfonated acid dyes. Computerized dosing pumps con trol the pH, the dyebath concentrations of the individual dyes, and th e total sorption of each dye during the process. This real-time, close d-loop adaptive control yields good reproducibility and uniform shade build-up in a laboratory dyeing machine. It is possible to reuse a dye bath containing residual dyes and chemicals from a previous dyeing.