Synthesis of polyhydric alcohol/ethanol phosphate flame retardant and its application in PU rigid foams

ABSTRACT Two types of polyhydric alcohol/ethanol phosphates (PAEPs) were synthesized by a two‐step reaction using phosphorus oxychloride, ethanol, and polyhydric alcohol (glycerol and pentaerythritol). First, phosphorus oxychloride was reacted with ethanol to form a mixture of diethyl chlorophosphate and tri‐ethyl phosphate, and then PAEPs were prepared by the reaction between the above mixture and polyhydric alcohol. The chemical structures of PAEPs were characterized by 1 H NMR, and the elemental compositions were analyzed by X‐ray photoelectron spectroscopy (XPS). The degradation behavior of the PAEPs and their solubility in polyols were studied. The results indicated the PAEPs could be well dissolved in polyols. When PAEPs were used as flame retardant for PU rigid foams at a content of 8 wt %, the char residue of polyurethane foam at 800°C increased from 17.2 to 28% in average, and the peak heat release rate (pHRR) of polyurethane foam decreased significantly from 207 to 133 kW/m 2 . In addition, PURF with PAEPs showed remarkable intumescent property. The results indicated that PAEPs were effective condensed phase flame retardant with char catalytic and intumescent property. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42298.