Self-cleaning textiles and coatings are making inroads in a variety of industries including those related to medical, architectural and fashion endeavors. Using hydrophilic and photocatalytic properties, self-cleaning textile technology allows fabrics to be cleaned simply by water without using cleaning agents. The photocatalytic component of these textiles can help decompose organics on the textile using the sun’s power.
So how sustainable or green are self-cleaning textiles and coatings? Titanium dioxide (TiO2) photocatalysis coating technology for the PVC-coated fabric shows excellent self-cleaning effect on its surface under irradiation of UV light, according to Dr. Hiroshi Toyoda of the Technical Research Center at Taiyo Kogyo Corporation, Osaka, Japan. And while fabric structures already provide environmental benefits, the TiO2 photocatalytic coating provides further benefits by decomposing nearby nitrogen oxide (NOx) pollution from automobiles and factories.
“Reducing energy costs and cleaning fees can save energy and enhance sustainability,” Toyoda says. “As more and more countries are enforcing stricter environmental laws, we believe TiO2 coated membranes will play a contributing role.”
TitanPE Technologies, Inc., a leading nano photocatalyst and the first hydrosynthetic photocatalyst manufacturer in Shanghai, China, is focusing on developing self-cleaning coatings because of its sustainable feature.
“TiO2 is much safer for the environment than other anti-stick or hydrophobic chemicals,” says Reinhard Liu, operations manager at TitanPE Technologies. “Its natural matter can be found in earth, so it is easy to join the natural cycle without problem. Our design of special nano particles can help the particle link together to form a big crystal film, and even if it is peeled off from the textiles, it is not in the form of small particles anymore. It will be a bigger micron-level crystal fragment so it is much safer. The acute oral toxic test of our material is the highest level, >10g/kg, which is actually non-toxic. And skin test about the products is, level 0, even better than most cosmetics. Fish can live in water that has had our liquid added, and once it is added into surface water, it will agglomerate together immediately and deposit to the bottom, not dispersing in water.”
Saint-Gobain’s Sheerfill is the only PTFE-coated membrane that is Cool Roof and Energy Star rated.
“Using Sheerfill can help earn LEED points, due to its excellent long-term solar reflectance,” says Michael Lussier, sales and market manager, architectural at Saint-Gobain, Melvern, Pa. “The use of Sheerfill with EverClean can significantly reduce energy costs—the translucency of the material drastically reduces the need for daylighting within the space below while increasing the comfort of the building occupants with diffuse, natural light.
The solar reflectance reduces heat gain below the Sheerfill, helping to reduce cooling loads and, again, creating a more comfortable environment. The EverClean topcoat has been shown to remove NOx from the air; 1,000m2 of Sheerfill with EverClean is equivalent to the NOx reduction capacity of about 90 trees.”
EverClean Topcoat TiO2 technology also positively impacts the environment. In the presence of UV light through a chemical reduction process, EverClean decomposes two atmospheric pollutants—nitrogen oxide and sulfur oxide. These pollutants, found in exhaust fumes and smoke, are major contributors to acid rain and urban ozone. The EverClean chemical reduction process releases nitrate ions that are eventually washed into the soil and help to fertilize plants.
Also, the amount of steel needed to support a lightweight Sheerfill structure is much less than that required to support a large traditional roof; this decreased requirement reduces the impact on the environment while helping to cut construction time.
“And with a 30-plus year life span, there is no need for regular replacement—which requires new material to be manufactured, more fabrication and deployment of people and equipment to install,” Lussier says. “Our first installation, done in 1973, is still in daily use at the University of La Verne in California, and still bears the original material.”
Maura Keller is a freelance writer and editor based in Plymouth, Minn.