News
17.01.2025

PIN S – K – Si FR for polycarbonate

A combination of a sulphonate potassium salt and polysiloxanes achieved UL 94 V-0 (1.6 mm) in polycarbonate. 1,3-benzenedisulphonic acid potassium salt (KSP, containing sulphur and potassium) at 0.03% loading and three different polysiloxanes (organic silicon containing molecules) at 1 – 3%, plus PTFE (PFAS anti-drip agent) 0.3% and an antioxidant 0.6% were compounded into polycarbonate (screw extruder) then injection moulded @ 285°C. The addition of the PIN FRs caused only small reductions in polycarbonate transparency, tensile strength and elongation at break. Fire performance was improved with all three of the polysiloxanes and at only 1% loading all three achieved UL 94 V-0 (1.6 mm, vs. v-2 for neat polycarbonate). The samples with 3% loading of polysiloxane showed up to +40% LOI, -45% peak heat release and -40% total smoke. The most effective of the three polysiloxanes tested was octaphenylsilsesquioxane.

“Enhancing the flame retardancy of polycarbonate through the synergistic effect of 1,3-Benzenedisulfonate acid dipotassium salt and phenyl polysiloxanes”, X. Zhang et al., J Appl Polym Sci. 2024; 141:e56071, https://doi.org/10.1002/app.56071