Foam application from a closed system – a study of machine and foam parameters
An attempt has been made to gain a greater insight into the interaction between foam and a moving textile substrate. The effects of changing wet pick–up, fabric velocity, liquid viscosity, foam density and mode of application on penetration have been studied. Application from a closed system makes it possible to apply an exact amount of liquid, and reflectance measurements revealed that between 10 and 60% wet pick–up the actual level of wet pick–up is of major importance. The amount of liquid available determines the likelihood of capillary transport. The results obtained in terms of fabric speed and foam density still leave questions to be answered on the mechanisms of foam flow and degradation in the textile.
Absorption and rheological phenomena during foam application on textiles
A simple rheological model has been used to describe foam flow through moving textile assemblies. The validity of this model was tested, and the nature and the relative magnitude of deviations from the model evaluated for several different substrates. Neglecting foam degeneration during transport, the model was found to represent a valuable means of evaluating some rheological and geometrical deviations. The model can be used in a semi-quantitative way to describe absorbency during foam application. Liquid absorption experiments done off-line, absorption during foam application and some earlier results could be described using different theoretical approaches. Some rheological anomalies have been discussed.
Foam Finishing of Cotton-Containing Textiles
A wet-processing technology which uses air instead of water as the primary diluent has been developed. The process consists of mechanically foaming a suitably formulated finish or dye formulation and then applying the foam to textile fabrics. Collapse of the foam distributes the finish on the substrate. The fabric is then subjected to conventional drying and fixing operations. The main advantage of the foam process resides in the substantial energy savings achievable in the drying of fabrics due to the replacement of water with air in the finish. Utilization of foams for the finishing of cotton and cotton/polyester fabrics are described. Plant data have established that energy savings as high as 70-80% can be achieved in foam finishing of cotton-containing textiles. In addition, in certain cases line speeds have been doubled. The foam process is currently used in plants for durable-press finishing, shrinkage control, and softener appli cation to a variety of cotton and polyester/cotton blend fabrics.