Durable water repellent processes

Perfluoroalkyl and Polyfluoroalkyl Substances (PFASs) include a family of fluorine-containing polymers with high performance properties used to make materials oil, stain and water resistant. These fluorinated polymers are widely used as textile finishes on workwear, uniforms, medical textiles, outdoor clothing and equipment.

During the textile production process, polymeric PFASs are used in a variety of applications, as treatments for textiles to enhance water, stain and oil repellence, which is commonly known as a Durable Water Repellent (DWR) finishing. Durable Water Repellent finishing is a process to impregnate a fabric in order to prevent or delay water moving into the fabric. However, over the last decade, concern has been raised regarding the possible discharge of long-chain PFASs into the environment. This includes long-chain DWR products, PFOS and PFOA. PFOS and PFOA are potential impurities in and potential degradation products from long-chain polymeric PFASs such as those used as DWRs. PFOS and PFOA resist degradation, possess toxic properties and bioaccumulate in the food chain and are now regarded as an emerging class of environmental contaminants.

PFOA is NOT used as a DWR or as an ingredient to produce polymeric DWR products. However, PFOA may be present as an impurity in long-chain commercial C8-based DWR products. For example, in the manufacturing of some long-chain repellents, 8:2 FTOH (8:2 fluorotelomer alcohol) is used as a raw material intermediate and is known to degrade to form PFOA.

• The common long-chain C8 DWR treatment for fabric consists of side-chain fluorinated polymers (mainly (meth) acrylates).
• Long chain raw materials such as 8:2 FTOH (fluorotelomer) and N-Me FOSE (ECF) used in the production of some side-chain fluorinated polymeric DWR products and present as impurities can be converted into PFOA through oxidation in the environment.
• 8:2 FTOH may be metabolically converted into PFOA through oxidation.

In 2006, major global suppliers of fluorinated DWRs were early adopters of the 2010/2015 PFOA Stewardship Programme which is the global partnership between the US Environmental Protection Agency and industry. The partnership is based on voluntary corporate goals to reduce human and environmental exposure to PFOA and higher homologues by eliminating those chemicals from facility emissions and product content by 2015.

Today short-chain alternatives are available. These include C6 DWR repellents based on fluorotelomer chemistry and C4 repellents, based on electrochemical fluorination chemistry (ECF).

PFOS and PFOA are classified as hazardous chemicals and have been regulated in some countries.