Substituent-Dyeing Properties Relationship of Disperse Dyes on Polyester in Low Pressure Waterless Dyeing System

Decamethylcyclopentasiloxane (D5) has attracted an increasing attention because it can realize waterless dyeing of chemical fibers. In this paper, two azo disperse dyes with different substituents were synthesized, and compared with C.I. Disperse Red 73 to study the relationship between structure and dyeing properties systematically in D5 media. The results showed that the dyeing uptake of dyes increased from 85.5 % to 98.0 % with the substituent changing from N-ethyl to N-acetoxyethyl group. This was because the solubility of dyes in D5 media showed an evident reduction. Although the dyes containing N-cyanoethyl group had the lowest solubility, the dyeing uptake became 93.4 %, which was slight lower than that of dyes with N-acetoxyethyl group. This was because an introduction of N-cyanoethyl group increased dye molecular aggregation in D5 media, making it difficult to diffuse. Additionally, the dyes with N-ethyl or N-acetoxyethyl groups showed better washing fastness and rubbing fastness than that of dye containing N-cyanoethyl group. These results provide a potential theoretical guidance for improving exhaustion of disperse dyes in waterless dyeing system. This study will promote textile industry sustainable development.