Application of Magnesium Hydroxide/Diphenoxy Phosphate in Silicone Rubber Flame Retardant Cable Material

Abstract

Deketoxime–type room–temperature vulcanized silicone rubber cable materials were prepared using α, ω–dihydroxy polydimethylsiloxane, carbon black, calcium carbonate, magnesium hydroxide, piperazine bis (diphenoxy phosphate) salt (PBDP), and melamine diphenoxy phosphate (MDP). The effects of carbon black and flame retardants on the mechanical properties, flame–retardant properties, and electrical insulation properties of silicone cable coatings were investigated. The research results showed that the products obtained had good mechanical and electrical insulation properties, with tensile strength greater than 3.0 MPa, dielectric strength greater than 22 kV/mm, and volume resistivity higher than 6.5 × 1014 Ω·cm. When 30 parts of Mg(OH)2:MDP = 2:1 are added to 100 parts of resin, the flame–retardant performance of wire and cable materials can be significantly improved. Under the thermal radiation illumination of 50 kW/m2, the ignition time (TTI) of the Mg(OH)2/MDP coating increased by 16 s, and the maximum heat release rate (pkHRR) and total heat release rate (THR) decreased by 29.7% and 68.8%, respectively, compared with silicone rubber without flame retardant. The silicone rubber coatings prepared were flame retardant up to the FV–1 level.