In order to solve the problems of low dye-uptaking and serious environmental pollution in the dyeing process of indigo dye. A branched waterborne polyurethane dispersant (WPU) was successfully synthesized from isophorone diisocyanate, trimethylolpropane and 2,4′-dihydroxybenzophenone. The structure and properties of WPU were characterized to prove that it could be used as a new dispersant to prepare liquid indigo dispersion. It could be clearly found that the D₅₀ of the prepared liquid indigo dispersion with WPU2 dispersant was less than 500 nm, D₉₀ was also less than 500 nm. Compared with powdered indigo dye, the K/S value of liquid indigo dispersion dyed fabric under the same conditions was about 11, which was twice that of powdered indigo dyed fabric. The UV resistance (UPF value) of the dyed fabric was about 272.72, which was triple that of powdered indigo dyed fabric, and its washing fastness was grade 3–4 and rubbing fastness was grade 4–5, demonstrating it also has excellent fastness like traditional powdered indigo, even slightly improved the staining fastness.

为解决靛蓝染料染色过程中上染率低、环境污染严重的问题。以异佛尔酮二异氰酸酯、三羟甲基丙烷和2,4'-二羟基二苯甲酮为原料成功合成了支化水性聚氨酯分散剂（WPU）。对WPU的结构和性能进行了表征，证明它可以作为一种新型分散剂制备液体靛蓝分散液。可以清楚地发现，用WPU2分散剂制备的液体靛蓝分散体的D ₅₀小于500 nm，D ₉₀也小于 500 nm。与粉状靛蓝染料相比，相同条件下液体靛蓝分散染色织物的K/S值约为11，是粉状靛蓝染色织物的2倍。染色织物的抗紫外线（UPF值）约为272.72，是靛蓝染色织物的三倍，其水洗牢度为3-4级，摩擦牢度为4-5级，表明它还具有出色的牢度，如传统的靛蓝粉，甚至略微提高了染色牢度。