Environmentally Friendly PTFE Use in Coatings

Environmentally Conscious PTFE Use in Coatings Recent years have seen growing concerns regarding PTFE usage, regulatory changes, and public criticism. Shamrock has addressed these concerns through PTFE waste recycling, final product manufacturing, and reduced PFOA levels in production. [1] Shamrock Chemicals was established in 1951 as a subsidiary of William D. Neuberg Company for the sale of powder wax. Shamrock's European headquarters in Tongeren opened in 2001. This was followed by the opening of the Tianjin facility in China in 2004. In 2007, a third facility was constructed in Kentucky. Shamrock's worldwide production facilities span six sites across three continents, exceeding half a million square meters. [2] Through this article, you will understand how we have reduced our environmental impact. PTFE is a unique polymer used in many applications. This polymer is valued for its unique properties; such as increasing slip for box coatings and wear resistance in inks. High temperature stability makes PTFE a valuable additive for high-temperature applications, including bobbins and powder coatings. Particles retain their shape and performance even above 250°C. [1] PTFE is one of the strongest polymers due to its C-F bonds. Over the last twenty years, PTFE has caused environmental and health concerns due to PFOA (perfluorooctanoic acid), an additive used in its polymerization. PFOA has been classified as a "forever chemical" due to its biological persistence, and its continuous use during the polymerization process has been banned. Alternative agents have been developed to enable this type of polymerization. [1] 

Recycled PTFE and Reduced CO2 Emissions

Shamrock has recycled more than 150 million pounds of PTFE, resulting in estimated savings of 1.5 billion pounds of CO2 emissions and unusable, environmentally persistent waste products. Shamrock has found that using recycled PTFE instead of 1 kg of virgin PTFE will reduce at least 10 kg of CO2 emissions. [1] Virgin PTFE polymer industrial-scale production occurs in a few stages [1]: 1. Calcium fluoride reacts with sulfuric acid to obtain anhydrous hydrogen fluoride for use in subsequent reactions. 2. The other starting material methane is reacted with elemental chlorine to obtain tri-chloromethane (chloroform). 3. Chloroform is fluorinated with anhydrous hydrogen fluoride to be pyrolyzed into TFE, becoming chlorodifluoromethane (CHClF2, also known as R-22). 4. Polymerization of the TFE monomer is carried out under controlled conditions to produce PTFE polymer. A model based on existing PTFE production facilities in the US was used to estimate CO2 emissions in PTFE production. The calculations detailed below show the amount of CO2 in PTFE production. [1] Estimated energy consumption of the model fluorochemical production facility:                                    Basic information for calculation: 761 kWh/MT Fluorochemical production + 96 Therm* Natural Gas/MT Fluorochemical production, Therm = 100,000 British Thermal Unit (BTU) or 29.3 KWh equals 100 cubic feet (2.83 m3) of natural gas at STP. [1] 

 Based on these figures, estimated total energy consumption for PTFE production: Electrical Energy: 761 kWh x 52,750 MT total production / 7,500 MT PTFE production = 5,400 kWh/MT PTFE Natural Gas: 96 Therm x 52,750 MT total production / 7,500 MT PTFE production = 680 Therm/MT PTFE Based on the estimated energy consumption above, the required amount of electrical energy and natural gas can be converted into equivalent CO2 emissions. [1] CO2 emissions from electrical energy: 5,400 kWh/MT PTFE x 1.10 kg CO2eq/kWh = 5,900 kg CO2eq/MT PTFE or 5.90 kg CO2eq/kg PTFE CO2 emissions from natural gas: 680 Therm/MT PTFE x 8,408 kg CO2eq/Therm = 3,700 kg CO2eq/MT PTFE or 3.70 kg CO2eq/kg PTFE Total: 9.6 kg CO2eq/kg PTFE. For every 1 kg of recycled PTFE, approximately 10 kg of CO2 emissions are prevented. 

PFOA in Micronized PTFE

Micronized PTFE (in ink and paint applications) may be desired to have lower molecular weight (MW). Lower molecular weight (MW) PTFE can be created through the degradation of high molecular weight (MW) PTFE. The degradation mechanism uses thermal and radiation-based processes. [1] PFOA and organic acids of other chain lengths are the result of degraded PTFE products. On 4 July 2020, the European Union published a REACH (EC) No: 1907/2006 regulation that came into force and requires PFOA concentration below 25 ppb in PTFE micronized products. On 8 April 2020, the POP Regulation (EU) 2019/1021 (Commission Delegated Regulation (EU) 2020/784) was extended until 4 July 2022 as 1,000 ppb. The European Union extended the 1,000 ppb limit and postponed the decision to reduce PFOA to 25 ppb. Companies wishing to sell to the European market must reduce their PFOA footprint. Shamrock has launched the "RC" micronized PTFE series to comply with the <25 ppb regulation.

Conclusion

At Shamrock, it is believed that seeking sustainable solutions and leaving a smaller environmental footprint is critical. Their work is focused on sustainability. Shamrock products reduce both PFOA and carbon footprint through PTFE recycling and rigorous manufacturing standards.  References  1. Shamrock "Environmentally conscious PTFE micropowder usage in coatings", 2022, 2. Shamrock Technology, https://shamrocktechnologies.com/, 2017, 3. Wikipedia, https://tr.wikipedia.org/wiki/Teflon, 21.04.2022, 4. Wikipedia, https://en.wikipedia.org/wiki/Perfluorooctanoic_acid, 06.09.2022  Dr. Hyun Seog Kim                                                                                                        Chemical Engineer Technical Service Group Director Shamrock Technologies  Eliz Türkileri Chemical Engineer Senior Technical Sales Manager Ravago Chemicals Turkey