Nylon can be flame retardant by halogen / antimony or other flame retardant synergistic systems. It can also be flame retardant by halogen-free flame retardant systems such as red phosphorus or melamine. From a quantitative point of view, the antimony halide synergy system is still the most widely used nylon flame retardant system. In some parts of Europe and Asia, efforts are being made to find alternatives to halogen flame retardants. But generally speaking, these alternative systems generally have problems such as low thermal stability or moisture absorption. For red phosphorus, there is also the problem of storage, because it is flammable. The following are the main flame retardants used in nylon and their respective advantages and disadvantages.

(1) Halogen-containing flame retardant system: the most important one and the most widely used abroad is brominated styrene polymer, which has extremely excellent thermal stability, and because it is melt-miscible with nylon, Therefore, it has good fluidity during processing. In addition, the flame-retardant nylon prepared with it also has superior electrical properties and good physical and mechanical properties. The limitation of this flame retardant is that it has poor light stability and is not yet fully compatible with nylon. In addition, its cost is higher than that of decabromodiphenyl ether, which is widely used in China. Another kind of flame retardant that has been used in nylon for many years is enemy flame. It is a chlorine-containing flame retardant, which has high flame retardant efficiency and electrical properties, but it has limitations in thermal stability. It is only suitable for nylon flame retardant systems with low processing temperature. Decabromobibenzyl ether is the most widely used flame retardant in China. Because of its higher bromine content, it has higher flame retardant efficiency to nylon and is the most economical flame retardant. But because it is a filler-type flame retardant, it has a great negative impact on the processing fluidity and the physical and mechanical properties of the product. In addition, its thermal stability and light stability are also poor. In recent years, a new flame retardant developed by people for flame retardant nylon is decabromodiphenoxyethane, which has the same bromine content and the same high flame retardant efficiency as decabromodiphenyl ether. It is also free of DPO (so-called dioxin) problems like brominated styrene polymers. In addition, it also has good thermal and light stability. Its limitation is that it is a filler-type flame retardant like decabromodiphenyl ether, and has poor compatibility with polymers, so it has poor processing fluidity and physical and mechanical properties. In addition, compared with decabromodiphenyl ether, the cost is higher.

       (2) Halogen-free flame retardant system: The widely used halogen-free flame retardants in nylon are red phosphorus and melamine salts. Red phosphorus has high flame retardant efficiency and can improve the arc resistance of products, but its storage and color limitations greatly limit its application in nylon, and it is generally only used in nylon 6. Another halogen-free flame retardant used in nylon is melamine salts, mainly melamine urate and phosphate. They have good flame retardant efficiency, but have poor thermal stability, and their products have poor electrical performance in humid environments due to their easy absorption of moisture.