A NEW MORE ECOLOGICAL CLEARING PRODUCT FOR DISPERSE DYES ON POLYESTER AND PE/CO BLENDS
ECO-CLEAR is a product developed pela Ecofoot for the clearing of disperse dyes, that is based on a physical process of clearing with inorganic nanoparticles. Removes insoluble dyes from the surface of the cotton and polyester fibres, without affecting the soluble reactive dyes that have reacted with cotton (cellulosic) fibres so it can be applied in the dyeing of polyester/ cotton blends, or polyester viscose blends, at the end of the whole process, saving:
The process of clearing the excess disperse dye left on the surface of polyester/cotton fibre blends cannot be avoided for most colours, since this dye will later stain adjacent fabric. The process which is usually applied is the reduction clearing process using alkaline sodium hydrosulphite. This is however a very polluting process, due to the high values of CQO and conductivity obtained as a result of its application. It is also a water intensive process and a long process too.
The reduction clearing on blends of CO/PE with sodium hydrosulphite is a very long process due to the intermediate rinses necessary before dyeing the cotton component with reactive dyes. Oxidative Clearing is a shorter process.
A – sodium carbonate to neutral pH ;
B – reactive dye (dosing) ;
C – Salt ; D –alkali ;
E – ECO-CLEAR
Results showed that clearing with ECO-CLEAR is a less polluting process, more sustainable and also has better fastness than the alternative reduction clear sequence. The inorganic amorphous nanoparticles are applied in alkaline washing-off bath of the reactive dyes, so that they will disintegrate during the process into soluble anionic salts, aiding the release of the hydrolysed reactive dye, and not leaving any deposit of the inorganic nanoparticles on the fibers or the effluent.