The invention relates to an active-dye low-salt dip
dyeing method for cotton fabric. A one-step process employed by the technology is excellent in
dyeing effect, and in the one-step process technology, a
salt substitute is applied to a pretreatment technology, pretreatment does not need individually performing, and the
processing process is shortened and water and energy are saved. Also, BOD5 and CODCr of a
processing raffinate of the one-step process technology are reduced compared with routine pretreatment, and the one-step process technology is environment-friendly. The low-salt
dyeing technology is capable of reducing the usage amount of
anhydrous sodium sulfate in the dyeing process by 50%, is excellent in dyeing effect, has the dyed fabric K / S value higher than that of a routine dyeing technology, and is uniform in obtained color. The soaping fastness and the
perspiration fastness are both high and are both 4-5 grade or more, the solarization fastness is 4 grade or more, and the dry / wet friction fastness is 4 grade or more. The improving capacity of the low-salt dyeing technology is better than that of a routine dyeing technology, in other words, the usage amount of a dye is less when same chroma is obtained, and the
dye uptake of the low-salt dyeing technology is far higher than that of a routine dyeing technology.