Permanent, Perfluorocarbon-free, Water-free Finishing of Textiles and Footwear
Gary S Selwyn, PhD
President,
Green Theme Technologies LLC
Albuquerque, NM 87107
Fluorocarbons have traditionally been used to provide a water and oil repellent finish on textiles used for sports apparel and footwear, recreational outer wear and other performance apparel, upholstery, military and technical textiles, carpet and nonwovens. Finishing is done using a water-based process, in which fabric is pulled through an emulsified, fluoropolymer solution and then is dried and heat cured in a large drying oven. This produces a product that has had acceptable and reproducible properties, but which also leads to a significant waste stream because of gradual bath contamination and exhaustion, as well as being a drain on clean water resources for many communities. Additionally, the required conversion of water to steam adds to energy consumption. However, from a green chemistry viewpoint, the worst aspect of this finishing technology is that the fluorocarbon treatment is gradually eroded by normal laundry cleaning that sends bio-persistent fluoropolymers into sewage treatment plants that are not equipped to remove these compounds and then into community watersheds, rivers oceans, and then eventually into the bloodstream of nearly every person on Earth.
This problem has attracted much recent attention because of the issue of perfluorooctyl acid (PFOA), which has been identified as a carcinogen. The manufacturing use of PFOA has been banned in the US and Europe and similar long chain alkyl perfluorinated compounds (PFCs) are similarly restricted. Shorter chain length PFCs are allowed, and are believed to be “safer”, but the evidence for this has been contested, especially since more PFCs of the shorter chain length are generally needed to achieve the same result as was previously obtained using longer chain length PFCs. Some environmental organizations have called for a total ban on PFCs.
In fact, PFCs are not needed for most textiles, including sports apparel and footwear, upholstery, carpeting and nonwovens. Hydrocarbon-based polymer chemistry provides superior water repellency and better stain removal properties than fabrics treated with fluoropolymers. Using an in-situ, free radical polymerization process that will be described, we are able to achieve a virtually permanent durable, water-repellent (DWR) finish on synthetics that lasts more than 100 laundry cycles andwhich does not contribute to water or air pollution, is energy-efficient, and uses no VOCs. It does not have oil repellency, but has superior stain-removal properties compared to the same fabric that has been treated with fluoropolymers.