Soil Resistant Finishes

 

I grew up with Scotchgard on sofas, Teflon on non-stick pans, and GoreTex on my raincoat. These trademarked items were all made possible through the vast PFC (perfluorocarbon) family of chemicals, which has transformed our lives – and the textile industry. When applied to fabrics, they provide water and stain resistance. These perfluorocarbons – commonly known as fluorocarbons – are among the most politicized and least understood chemicals used in the textile industry. Until recently, they were thought to be biologically inert. No one thinks so now.

The multi-billion-dollar "perfluorocarbon" (PFC) industry has emerged as a regulatory priority for scientists and officials at the U.S. Environmental Protection Agency (EPA) because of a flood of disturbing scientific findings which have been published since the late 1990s. These findings have elevated PFCs to the rogue's gallery of highly toxic, extraordinarily persistent chemicals that pervasively contaminate human blood and wildlife the world over. Government scientists are especially concerned because, unlike any other toxic chemicals, the most pervasive members of the PFC family never degrade in the environment.

Here is a quick dictionary of perfluorochemicals from the Environmental Working Group to give you an overview:

  • Perfluorinated chemicals or Perfluorochemicals (PFC): A chemical family consisting of a carbon backbone surrounded by fluorine, which makes them impervious to heat, acid, or other forces that typically break down chemical compounds. Sometimes referred to as 'Teflon' chemicals.
  • Fluorotelomer: Chemicals that become PFCs when they are released into the environment. These are the chemicals applied to food packaging, stain-resistant clothing, and carpet protection.
  • PFOA: Perfluorooctanoic acid. It is the breakdown product of fluorotelomers and the backbone of many consumer products. Additionally, they are also used as a surfactant to produce PTFE, the Teflon in pans, sometimes called C8.
  • PFOS: Perfluorooctanol sulfate. It is the breakdown product of fluorotelomers based on 3M chemistry.
  • C8, C6, et al: These are a range of chemicals that are identical to PFOA but with carbon backbones of varying length. PFOA/C8 has 8 carbons; C7 has 7, and so on. These are breakdown products of fluorotelomers.
  • PTFE: Polytetrafluoroethylene. This is a polymer used for cookware and other non-stick applications. Brand names include Teflon and Silverstone. A physically expanded form of PTFE is used to make Gore-Tex. PFOA is an ingredient in the manufacture of PTFE.
  • Teflon: Teflon is a brand name; it is not a single chemical. Teflon can refer to PTFE or a fluorotelomer or any number of perfluorochemicals – it is based on C8 chemistry, and PFOA is a byproduct of the manufacturing of PTFE used in the Teflon chemistry. Perfluorochemicals are often termed "Teflon" chemicals or as having "Teflon" chemistry.
Perfluorocarbons break down within the body and in the environment to PFOA, PFOS, and similar chemicals. (Note: the chemistry here is quite dense; please let us know if we made a mistake!) They are the most persistent synthetic chemicals known to man. Once they are in the body, it takes decades to get them out – assuming you are exposed to no more. They are toxic in humans with health effects from increased cholesterol to stroke, and many studies link them to birth defects, developmental delays, and cancer.[1]

Alarmed by the findings from toxicity studies, the EPA announced on December 30, 2009, that PFC's (long-chain perfluorinated chemicals) would be on a "chemicals of concern" list and action plans could prompt restrictions on PFC's and the other three chemicals on the list.[2]

Although little PFOA can be found in the finished product, the breakdown of the fluorotelomers used on paper products and fabric treatments might explain how more than 90% of all Americans have these hyper-persistent, toxic chemicals in their blood. A growing number of researchers believe that fabric-based, stain-resistant coatings, which are ubiquitous, maybe the largest environmental source of this controversial chemical family of PFCs.[3]

Studies have confirmed a significant association between these chemicals and thyroid disease in women[4], and early-onset menopause[5]. They have also been linked to thyroid cancer, immune system problems, and heart disease. Researchers also believe they act as hormone disruptors in the body.[6]

There are many finishes on the market that claim to provide soil and stain repellants for fabrics. Among the more well known are:

  • Scotchgard
  • Teflon
  • Zepel
  • NanoTex
  • GreenShield
  • Crypton Green
Each one of these finishes uses fluorocarbon chemistry to achieve their results - it’s just that they each go about it a bit differently. 
There has been a lot of information on 3M, DuPont, and their two products, Scotchgard and Teflon, on the web. The Environmental Working Group (http://www.ewg.org/ ) has detailed descriptions of what these chemicals do to us, as well as the information on the many suits, countersuits, and research studies. The companies say their new reformulated products are entirely safe – while other groups such as the Environmental Working Group question this assumption.
Recently, a new dimension was added to stain-resistant formulations, and that is the use of nanotechnology.
For scientists who were trying to apply nanotechnology to textile soil and stain repellency, they turned, as is often the case in science, to nature. Studying the surface of lotus leaves, which have an incredible ability to repel water, scientists noticed that the surface of the lotus leaf appears smooth but is actually rough and naturally dirt and water repellent. The rough surface reduces the ability of water to spread out. Tiny crevices in the leaf’s surface trap air, preventing the water droplets from adhering to the service. As droplets roll off the surface, they pick up particles of dirt lying in their path. Using this same concept, scientists developed a nanotechnology-based finish that forms a similar structure on the surface of the fiber. Fabrics can be cleaned by simply rinsing with water.
Nano-Tex (www.nano-tex.com) was the first commercially available nanoparticle-based soil repellant fabric finish. It debuted in December of 2000. Another nanotech-based soil repellant is GreenShield (www.greenshieldfinish.com) which debuted in 2007. Both these finishes, although they use nanotechnology, also base their product on fluorocarbon chemistry. Nano-Tex’s website does not give much information about their formulation – basically, they only say that it’s a new technology that “fundamentally transforms each fiber through nanotechnology”. You will not get much more in the way of technical specifications out of Nano-Tex. GreenShield is much more forthcoming with information about its process.
In the GreenShield finishes, the basic nanoparticle is amorphous silica, an inert material, that has a well-established use in applications involving direct human consumption. It is generally recognized as safe, approved by the Food and Drug Administration (FDA) and Environmental Protection Agency for such applications. The use of silica enables GreenShield to reduce the number of fluorocarbons by a factor of 8 or more from all other finishes. It reduces overall chemical load by a factor of three – making GreenShield the finish which uses the least amount of these fluorocarbons.
The GreenShield finish gets mixed environmental ratings, however. Victor Innovatix’s Eco Intelligent Polyester fabrics with GreenShield earned a Silver rating in the Cradle to Cradle program. However, the same textile without the GreenShield finish (or any finish) earned a higher Gold rating, reflecting the risk of toxicity introduced to the product by GreenShield. 

 

[1] Environmental Working Group on toxic chemicals 
[2] The other three chemicals on the list are polybrominated diphenyl ethers (PBDEs), phthalates, and short-chain chlorinated paraffin (SCCPs). Three of these four chemicals are used in textile processing.) 
[3] Le Marechal, Alenka, et al; "Textile Finishing Industry as an Important Source of Organic Pollutants" University of Maribor, Environmental Protection Institute, Maribor, Slovenia http://cdn.intechopen.com/pdfs-wm/29368.pdf
[4] Knox, SS, et al, “Perfluorocarbon exposure, gender and thyroid function in the C8 Health Project”, Journal of Toxicological Science, August 2011: 36(4):403-10. 
[5] Knox, Sarah S., et al. “Implications of Early Menopause in Women Exposed to Perfluorocarbons”. Clinical Endocrinology & Metabolism. 96(6):0000-0000, June 2011. http://jcem.endojournals.org/content/96/6/1747.abstract
[6] Derbyshire, David. “Could your Saucepans Bring on the Menopause? Chemicals Found Around the Home Linked to Health Problems”. Health &Wellness: Sott.net. 24 Mar. 2011.
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