Abstract: In order to solve the dyeing problem of polypropylene fibers, high-hydrophobic dyes with ultra-high hydrophobicity and good structural planarity are selected to dye polypropylene fibers, and their dyeing properties are discussed. The experiment discussed the effects of dyeing temperature, time,the dosage of dispersant and pH value on the color depth, and measured the dyeing thermodynamic parameters of high hydrophobic dyes on polypropylene fibers. Results indicated that high hydrophobic dyes have good dyeing performance for polypropylene fibers. The optimized dyeing condition is as follows: the dyeing temperature is 120 ℃ for 60 minutes, the concentration of dispersant is 0.1%～0.3 %,and the pH value is 4～5. Methyl yellow dye and Sudan B dye with azo structure have high affinity and distribution coefficient to fibers. And reduce the molar volume of dye molecules can improve the affinity and distribution coefficient of the high hydrophobic dyes to the polypropylene fibers.

Key words: polypropylene fiber; high hydrophobic dye; dyeing; affinity