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

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.