DESIGN AND PERFORMANCE OF A TECHNICALSCALE MACHINE FOR POLYESTER DYEING IN SCCO_2

摘要

A technical-scale textile dyeing machine has been designed, built and tested for the dyeing of polyester cloth in supercritical carbon dioxide (scCO_2). To minimise the process cost, a new type of pressure vessel and a new type of centrifugal pump were developed. The dyeing vessel is a stainless steel liner, reinforced with carbon fibres to take up the radial pressure forces. The axial forces, working on the lids of the vessel, are taken up by an external yoke. A low-pressure centrifugal pump, used to circulate the scCO_2 through the dye and the polyester, has been designed for service in a scCO_2 environment and placed inside the dyeing vessel. Tests proved that it is possible to dye polyester batches of 2 kg in a two-hour process. Per batch, 95% of the CO_2 was recycled. The polyester was dyed evenly, had good fastness properties, did not exhibit excessive shrinking and it showed no change in tensile strength, indicating that the dyed product was of the same quality as in aqueous dyeing.