Abstract: Because of the surface and the performance of polyester filament and microporous modified PET are very different, which lead to the inconsistent shade when even dying with one-bath process. Identified the reduction of oxygen bleaching pre-treatment process of polyester filament and microporous modified PET by alkali resistance tests: Ratio 1:30 , concentration of caustic soda 6g / L, degreasers of high temperature 0.4g / L,130℃ degrees for 20min; In order to reduce the inconsistent shade , filtering the disperse dyes, identified the tricolor dyes: JRB blue, JFG yellow, JFRB red, which gives the two fiber relatively higher surface color depth value K/S, smaller color difference Δ E , and the better union dying. And also discussed the impact of dye concentration , dyeing time , dyeing temperature , dyeing pH value on union dying of the polyester filament and microporous modified PET fiber.

Key words: polyester filament, microporous polyester fiber, one-bath process, homochromy