Application of organophosphorus flame retardant in PC/ABS alloy:
Organophosphorus flame retardants mainly refer to phosphate ester flame retardants, which are one of the most important varieties of PC/ABS alloy halogen-free flame retardants, with dual effects of flame retardant and plasticization. Its flame retardant mechanism is: on the one hand, it is thermally decomposed to generate phosphoric acid, metaphosphoric acid, etc., which can catalyze the endothermic dehydration of hydroxyl-containing compounds into carbon reaction, so that a dense carbon layer is formed on the surface of the polymer; on the other hand, it is heated to generate PO•, which can Capture H• and HO• to inhibit combustion reaction.
It has important application value. The most representative phosphates are triphenyl phosphate (TPP), resorcinol-bis (diphenyl phosphate) (RDP) and bisphenol A-bis (diphenyl phosphate) ( BDP). Among them, TPP is a flaky solid, but its melting point is low, and the feeding port will be bridged. It is necessary to strictly control the processing temperature during extrusion, otherwise the loss will be large. RDP and BDP are liquids, and they need to be pumped in by a metering pump during processing. Especially, the viscosity of BDP is high, which brings difficulties to processing. The research of K.H. Pawlowski et al. believes that for PC/ABS alloys, TPP plays a flame retardant role in the gas phase, RDP mainly plays a flame retardant role in the gas phase and also has a solidified phase flame retardant, and BDP mainly plays a flame retardant role in the solidified phase at the same time. There are also gas phase flame retardant. From the limiting oxygen index (LOI) test, the flame retardant effect of TPP and RDP is slightly better than that of BDP, while the result of the cone calorimetry test is that BDP is the best. In PC/ABS alloys with ABS content not exceeding 30%, TPP is generally added at 12% to 18%, RDP is generally at 8% to 12%, and BDP generally needs to be added at more than 12% to reach UL94-V0 level.
