Water and oil repellent coating on fabric using hollow cathode PECVD

Abstract

Thin film deposition is a suitable process for textile finishing at a time when environmental protection is a global concern. Thin film technology for textile treatments does not only avoid the harmful chemistry and resulting hazardous waste of the wet chemistry, but limits the use of chemicals, water, etc., and do not require a drying system, resulting in a much lower energy consumption. The hollow cathode plasma enhanced chemical vapor deposition is one of the alternatives developed to overcome the wet processings disadvantages. Water and oil repellent finishes are applied through plasma polymerization of short chain perfluoroalkyls precursors. The key advantages of this technology are a high deposition rate and a good uniformity over large areas. However, hollow cathode is a high-density plasma source, appropriate for the deposition of inorganic layers, typically SiO2, but challenging for the deposition on fabrics without modifying their bulk properties or damaging their surface.In this work, we demonstrate the successful use of the hollow cathode technology to impart water and oil repellent properties on polyolefin textiles with fluorinated and silicone precursors. The effect of parameters such as power, pressure, gas composition and flow on water and oil repellency have been evaluated according to international standards, water contact angle and the film composition analysed through FTIR measurements. Water contact angles greater than 150°, i.e. superhydrophobic surface, and oil repellency grade of 4 have been obtained.