Effect of partial replacement of antimony trioxide with zinc borate and stannic oxide on the flame retardancy of flexible PVC films

Abstract Replacing antimony trioxide (Sb 2 O 3 ) with an environmentally friendly alternative is of great scientific and commercial value for studying the flame retardant properties of flexible PVC (fPVC) films in automotive interior materials. This study develops flame retardant fPVC films with reduced Sb 2 O 3 content by introducing stannic oxide (SnO 2 ) and zinc borate (ZB). The results indicate that the fPVC film with ZB partially replacing Sb 2 O 3 exhibits superior flame retardancy and smoke suppression compared to the product containing SnO 2 . The peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of 2ZB/2Sb 2 O 3 fPVC film are reduced by 32.1%, 27.5%, and 22.1%, respectively, compared to that of 4Sb 2 O 3 contained fPVC film. The increase in flame retardancy is attributed to the presence of ZB, which compensates for the deficiency of char formation ability of Sb 2 O 3 in the condensed phase. The PHRR and THR of 2SnO 2 /2Sb 2 O 3 fPVC film decrease by 27% and 12.5%, respectively, compared to that of 4Sb 2 O 3 fPVC film, while the TSR increases by 16.5%. This study develops a straightforward approach to creating a flame retardant fPVC film that is suitable for the latest industrial application in automotive interior materials.