Hydroxyethylidene diphosphonic acid‐modified starch‐based flame retardant in improving the flame retardancy of insulating paper

Abstract In order to improve the flame‐retardant performance of insulating paper and reduce the fire risk, hydroxyethyl diphosphate and dicyandiamide were used to modify starch to prepare a new starch‐based flame retardant (SHPD). The combustion, mechanical, and electrical properties of SHPD treated flame‐retardant insulating paper were investigated. The results showed that when the impregnation concentration of SHPD was 25.0%, the limiting oxygen index of the insulating paper was increased from 18.3% to 38.3% and reached the level of UL‐94 V‐0. The tensile index and burst index of the flame‐retardant insulating papers were only 10.17% and 12.5% lower than that of the control insulating paper. The ring crush strength and alternating current breakdown strength in air of the flame‐retardant insulating papers were 63.3% and 1.8% higher than that of the control insulating paper. The SHPD flame retardant has a good application prospect in insulating paper.