Adrian Beard, pinfa and Clariant
The EU’s “Chemical Strategy for Sustainability” (April 2022, pinfa Newsletter n°138) will bring major changes to chemicals regulation in Europe and these are today being initiated, including the recast of the EU chemicals regulation REACH, the concepts of “Safe and Sustainable by Design” (SSbD) chemicals and of “Essential Uses” of certain chemicals, the announced Restriction of all PFAS (as a class of chemicals). The update of CLP includes a new Hazard Category “M” (mobile). The REACH recast is expected to require Registration of some polymer and declaration of all polymers.
The Restriction of PFAS chemicals could pose challenges to formulating FR polymer compounds because it may prevent the use of PTFE as an anti-drip agent, whereas this is currently needed at low doses (generally <0.5%) to avoid flaming dripping which result in failure of UL 94 V-0 and corresponds to a risk of spreading fire in real life.
The Chemicals Strategy for Sustainability will be implemented for flame retardants through the ECHA Flame Retardants Strategy (see above). This identifies a number of brominated FRs as priorities for Restriction, identifies a range of nitrogen and inorganic FRs are requiring no regulatory action and concludes that some groups of organophosphorus FRs are “low or unlikely hazard”. Further assessment of other groups of organophosphorus is expected after brominated FRs have been assessed and regulated by 2025 or later.
Clariant is already working to apply the principle of Safe and Sustainable by Design (SSbD) chemistry to the company’s FRs using a range of 39-criteria, including comparison to the market standard FR solution. Significant challenges for organophosphorus FRs are the energy requirement for P4 production and the current use of toxic vector chemicals in the manufacturing chain (PCl3, PH3).
Clariant’s work on application of Safe and Sustainable by Design (SSbD) chemistry shows that it is very difficult to combine desirable SSbD chemical properties with application requirements for FRs: degradability tends to be contradictory to product durability and to recyclability and non-bioaccumulation to polymer compatibility. Biobased phosphorus FRs are today widely researched, but challenges of thermal stability (compatibility with polymer processing) and water uptake are obstacles to industrial implementation. At the same time, application requirements are becoming increasingly demanding and FRs must be compatible with necessary mechanical performance, miniaturisation, electrical insulation (CTI).
Phosphorus chemistry offers positive perspectives to address these challenges, with high flexibility, fire safety action in both solid (char) and gas (radical quenching) phases, additive, reactive and polymeric chemistries.