Dyeing properties of polylactic acid fabric with disperse dyes of different structures using decamethylcyclopentasiloxane as non‐aqueous media

Abstract Polylactic acid (PLA) fibre, as a renewable and biodegradable synthetic polymer, is attracting increasing attention in the field of textiles. However, there are still some problems associated with PLA fibre dyeing, with a traditional water bath using disperse dyes restricting its industrialisation. Waterless dyeing, as a green and environmentally friendly dyeing method for PLA fibre, is expected to replace the traditional water bath dyeing method. However, the disperse dyes suitable for PLA fibre are different from those that are suitable for traditional poly(ethylene terephthalate) fibre. In the current study, the waterless dyeability of PLA fibre using disperse dyes with different chemical structures, and decamethylcyclopentasiloxane (D5) as the media, was investigated. First, the optimal dyeing process conditions of dye concentration, dyeing temperature, dyeing time and liquor ratio for PLA waterless dyeing were determined. The results indicated that the most suitable dyeing process conditions were: a dye concentration of 5%, dyeing temperature and time of 120°C and 40 minutes, respectively, and a liquor ratio of 1:10. Next, PLA was dyed with 10 disperse dyes with different structures using the determined optimum dyeing process conditions to compare their dyeing properties. The results showed that there were obvious differences in the K/S values for PLA dyed with dyes of different structures. The K/S values for PLA dyed with monoazo structure dyes were significantly higher than those for anthraquinones and heterocyclic structure dyes. Disperse dyes with a monoazo structure are suitable for PLA waterless dyeing. This study provides a research basis to develop suitable dyes for waterless dyeing PLA using D5 as the media.