Synthesis of novel nitrogen‐phosphorus flame retardants and their flameproof to flammable polymers

Abstract To prepare the efficiently flame retardants (FR) for the highly flammable polymers, the novel nitrogen‐phosphorus based FRs (P‐N FR) (PN‐3, PN‐4, PN‐5, and PN‐6) were prepared via phosphorus halides and amine derivatives with 40‐90 % in yields. The appearances of P‐N FRs are lightly white solid. All P‐N FRs are water‐insoluble and show a melting point above 40 o C. The success of the synthesis was confirmed by NMR analysis. Both 1 H and 31 P NMR data show clearly the same as the predicted chemical shift signals. The thermal stability behavior of these FRs was studied via TGA analysis. Thermal decomposition occurs in the range of 220‐260 o C under N 2 gas. The 80% of a mass loss with one step decomposition and 5‐20% of the char residues at 700 o C were obtained. The UL‐94 test with self‐extinguishing behavior on ABS and EVA was realized at 20‐25wt% loadings of P‐N FRs. It was observed that the addition of 18‐20 wt% of PN‐5 acquires UL‐94 V‐0 rating for the highly flammable resins (ABS and EVA) whereas to achieve the UL‐94 V‐0 rating, 20‐30 wt% of loadings of PN‐4 and PN‐6 are needed. It was concluded that the structure moieties of P‐N FR affect its FR behaviors.