Textile Dry Cleaning Using Carbon Dioxide: Process, Apparatus and Mechanical Action

Abstract

Fabrics that are sensitive to water, may wrinkle or shrink when washed in regular washing machines and are usually cleaned by professional dry cleaners. Dry cleaning is a process of removing soils from substrate, in this case textile, using a non-aqueous solvent. The most common solvent in conventional dry cleaning is perchloroethylene (PER). Despite its satisfactory cleaning performance, PER has several drawbacks. One approach is to develop an alternative solvent for PER. CO2 is chosen in this study because it has several advantages compared to the other alternative solvents. The main objective of this study is to improve the cleaning performance of CO2 dry cleaning for particulate soils, firstly by studying and solving the redeposition problem, secondly by enhancing the amount of mechanical action applied to the fabric. Another objective of this thesis is to achieve more insight in the cleaning process since little information is available regarding the textile movement inside the rotating drum in the CO2 medium. This has been studied with an endoscopic camera in the 25 L CO2 dry cleaning machine. Experiments with an observation cell equipped with a mechanical actuator were performed to apply well defined forces on the textile, and use these results to perform a quantitative analysis of the mechanical forces. Based on the results of the above, an ideal CO2 dry cleaning machine and process has been designed. This is a combination of best practices, new insights obtained from the results of this study and the best available technologies. The performance and the investment costs of CO2 dry cleaning are not yet comparable with the conventional solvents or the other alternative solvents. However, we believe that CO2 is the only real green solvent for textile dry cleaning and our studies have shown that it has a high potential to replace PER in the future. The economy evaluation also showed that the operating costs for dry-cleaning using CO2 are comparable to the costs using PER.