Ultrasound application in dyeing industrial processes

The application of ultrasound (US) in dyeing and washing industrial treatments is an important research theme because, as can be seen from a literature survey, this technique seems to be able to reduce the environmental impact and costs of these fundamental processes. In the frame of the Regional Project INTEXUSA (Intelligent Innovation for Sustainable Textile Production: Optimisation of dyeing processes with UltraSonic Technology and its integration with automatic on-line control), concerning the use of ultrasound energy for the intensification of dyeing and washing processes, a preliminary study was carried out to verify how ultrasound application, at different operative condition, might change the mechanical properties of wool fibers, and eventually damage them or the fabric structure. Preliminary trials were performed using a pilot apparatus, equipped with two different types of ultrasound transducers: -a rectangular flat one (dimensions of 415 x 325 mm) with a power of 600 W and variable frequency in the range of 25 - 120 kHz; -a cylindrical one, 500 mm length and 60 mm diameter, 1 KW power and a fixed 28 kHz frequency. The experiments were carried out with a significant quantity of fabric that can lie still or move over the ultrasonic transducer with variable power and frequency. Different configurations have been tested changing the distance of the fabric from the transducers, the residence time of the material in the ultrasonic field, the power amplitude and the frequency of the transducers.