Anthraquinone and Azo Dyes in Dyeing Processes of PET Films and PET Knitted Fabrics Using Supercritical CO2 Medium

Abstract

AbstractSummary: Dyeing processes using supercritical fluid present advantages over the conventional dyeing process using aqueous medium. Previous works from our group on polymeric fibers such as N,N‐dimethylacrylamide (DMAAm) modified poly(ethylene terephthalate), PET, showed higher sorption of disperse dyes in supercritical medium. Furthermore, recent studies showed that the association of UV radiation and DMAAm treatment leads to a better incorporation of dyes in modified PET soaked in aqueous medium. In this work, modified and non‐modified PET knitted fabrics (KF) were dyed in supercritical CO2 medium. Azo and anthraquinone dyes were used in order to compare the extent of incorporated dye in PET films and PET KF in supercritical CO2. The dyeing process variables were studied by factorial design and by a response surface methodology (RSM) technique. The anthraquinone dye presented a better incorporation in PET than the azo dye. The UV light exposure and the dyeing times inputs showed positive main effects in the incorporation of dyes in PET films and PET KF. From the RSM data, DMAAm and UV light modified PET KF presented 7.43 mg of incorporated azo dye by g of PET if the optimized dyeing conditions, time: 135 min and pressure: 212 bar would be used. In the respective optimized dyeing conditions for the anthraquinone dye, time 150 min and pressure 229 bar, the incorporated dye would be 22.9 mg of dye by g of PET.