PTFE as a Flame Retardant Additive: Synergy with Phosphorus and Nitrogen Systems

Traditional phosphorus-based and nitrogen-based flame retardant systems are the most widely used environmental protection flame retardant technologies in polymer industry, with the advantages of low toxicity, low smoke and high flame retardant efficiency. However, single phosphorus-nitrogen flame retardant systems have obvious application defects: excessive addition will reduce the mechanical properties and processing fluidity of materials, and the flame retardant endurance in high-temperature environments is poor, which is easy to cause flame retardant failure under long-term thermal radiation. PTFE micro-powder, as an efficient auxiliary flame retardant additive, can form an excellent synergistic flame retardant system with phosphorus and nitrogen flame retardants, significantly improve the comprehensive flame retardant performance of polymer materials, and solve the performance bottlenecks of single flame retardant systems. This synergistic technology has been widely used in the modification of engineering plastics, rubber and composite flame retardant materials PTFE SHEET.

The synergistic flame retardant mechanism between PTFE and phosphorus-nitrogen systems includes gas-phase flame retardancy and condensed-phase carbon formation promotion. The phosphorus-nitrogen flame retardant system mainly plays a role in condensed phase flame retardancy. Under high-temperature combustion, it can decompose to generate phosphoric acid compounds and nitrogen inert gas, promote the formation of dense carbon layer on the material surface, isolate oxygen and heat, and inhibit material pyrolysis and combustion. However, the carbon layer formed by single phosphorus-nitrogen system has loose structure and poor high-temperature stability, which is easy to crack and fail under continuous flame impact. After adding PTFE micro-powder, the fluorine-containing groups decomposed by PTFE can cross-link with phosphorus-nitrogen compounds to form a more compact and high-temperature resistant fluorine-phosphorus-nitrogen composite carbon layer, which greatly enhances the structural stability and barrier protection ability of the carbon layer.

In the gas-phase flame retardant stage, PTFE and phosphorus-nitrogen systems produce obvious complementary synergistic effects. Phosphorus-based flame retardants generate free radical quenching groups in the gas phase to inhibit flame chain reaction, and nitrogen-based flame retardants release inert gases such as nitrogen and ammonia to dilute oxygen and combustible gas concentration. PTFE decomposes to produce high-activity fluorine free radicals, which can capture high-energy combustion active free radicals that cannot be completely eliminated by phosphorus-nitrogen systems, thoroughly terminate the flame combustion chain reaction, and significantly improve the self-extinguishing speed of materials. The composite synergistic system realizes the full coverage of gas-phase and condensed-phase flame retardancy, and the flame retardant efficiency is far higher than that of single flame retardant system.

In terms of material processing and mechanical performance protection, PTFE additives have unique synergistic advantages. Traditional high-dose phosphorus-nitrogen flame retardants will cause material brittleness, reduced tensile strength and poor processing fluidity. PTFE micro-powder has ultra-low friction and excellent dispersion performance. When compounded with phosphorus-nitrogen flame retardants, it can improve the internal lubricity of the material, optimize processing fluidity, and offset the mechanical loss caused by excessive flame retardant addition. While improving the flame retardant grade of materials, it maintains the mechanical toughness and dimensional stability of the matrix materials, realizing the perfect balance of flame retardant performance and mechanical performance. The optimized synergistic formula is widely used in the production of high-performance flame retardant PTFE TUBE and modified polymer products.

A large number of experimental studies have proved that the composite flame retardant system of PTFE and phosphorus-nitrogen can significantly improve the limiting oxygen index, vertical combustion grade and smoke suppression performance of polymer materials. Under the same addition amount, the flame retardant efficiency of the synergistic system is increased by more than 35% compared with the single phosphorus-nitrogen system, and the smoke density and toxic gas emission during combustion are significantly reduced. In high-temperature combustion environments, the synergistic system still maintains stable flame retardant performance, avoiding the rapid failure of single phosphorus-nitrogen flame retardants at high temperature. In addition, the PTFE synergistic system has excellent weather resistance and aging resistance, and the flame retardant performance will not be attenuated after long-term outdoor and high-temperature aging.

To sum up, PTFE, as an efficient synergistic flame retardant additive, can make up for the deficiencies of traditional phosphorus-nitrogen flame retardant systems, build a multi-dimensional composite flame retardant mechanism of gas phase and condensed phase, and improve the flame retardant efficiency, high-temperature stability and comprehensive performance of materials. The synergistic technology of PTFE and phosphorus-nitrogen systems provides a new technical path for the development of high-efficiency, low-toxicity and high-stability environmental protection flame retardant materials, and has broad application prospects in electrical, construction, automotive and aerospace flame retardant fields.