Posted on 21/07/2019 in 2019
Modified rectorite improves PIN intumescent coating

The natural mineral clay rectorite (which contains aluminium, calcium, silicon and sodium) was modified by reaction with sodium pyrophosphate then tested at 10% in a waterborne PIN intumescent fire retardant coating, consisting of ammonium polyphosphate, melamine, titanium oxide and pentaerythritol. A 2 mm coating was applied to 5 mm steel plates by brush. The coatings were tested with a non-standard test method, using alcohol burning on the steel plates’ surface as the heat source for 60 minutes. With no intumescent coating, the back of the steel plates reached 200°C in 30 minutes, whereas the temperature with the intumescent coatings was around 20% lower. At 60 minutes, the control and the standard intumescent coating plate both reached around 225°C whereas the plate with the coating including modified rectorite only reached around 200°C. The authors conclude that this modified rectorite clearly improved the intumescent coating on steel, enabling generation of a more uniform and compact intumescent foam structure, giving a ceramic-like effect protecting the foam and improving adhesion to the steel plate.

“An emerging mineral-based composite flame retardant coating: Preparation and enhanced fireproof performance”, W. Xie et al., Surface & Coatings Technology 367 (2019) 118–126
See also the summary of UL fire testing of upholstered furniture in pinfa Newsletter n°102

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