Nylon can be flame retardant by halogen/antimony or other flame retardant synergistic systems, and can also be flame retardant by halogen-free flame retardant systems of red phosphorus or melamine. From the point of view of quantity, the halogenated/antimony synergistic 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 in general, these alternative systems have problems with low thermal stability or moisture absorption. In the case of red phosphorus, there is also the problem of storage, since it is inherently flammable. Here are the main flame retardants used in nylon and their advantages and disadvantages.

(1) halogen-free flame retardant system: The most widely used halogen-free flame retardants in nylon are red phosphorus and melamine salts. Red phosphorus has a high flame retardant efficiency and can improve the arc resistance of the product, but its storage and color limitations greatly limit its application in nylon, generally only used in nylon 6. Another halogen-free flame retardant used in nylon is melamine salts, mainly melamine urate salts and phosphates. They have good flame retardant efficiency, but poor thermal stability, and because of easy moisture absorption, the electrical properties of the product are poor in humid environments.

(2) halogenated flame retardant system: one of the most important is also the most widely used in foreign countries is brominated styrene polymer, it has extremely superior thermal stability, and because it is fused with nylon mismix, so in the processing process has a good fluidity. In addition, the flame-retardant nylon prepared with it also has superior electrical properties and better physical and mechanical properties. The limitation of this flame retardant is that the light stability is poor and it is not completely compatible with nylon. In addition, its cost is higher than that of decabromodiphenyl ether, which is widely used in China. Another flame retardant used in nylon for many years is anticombustible, it is a chlorine-containing flame retardant, with high flame retardant efficiency and electrical properties, but its limitations in terms of thermal stability make it only suitable for nylon flame retardant system with low processing temperature. At present, the most widely used flame retardant in China is decabromodiphenyl ether, which has a higher flame retardant efficiency for nylon due to its higher bromine content, and is the most economical flame retardant. However, 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 for use in nylon flame retardancy is decabromodiphenyl ethane, which has the same bromine content and the same high flame retardancy efficiency as decabromodiphenyl ether, and is as free of DPO(so-called dioxins) as brominated styrene polymers. In addition, it also has good thermal and light stability. Its limitation is that it is the same filler flame retardant as decabromodiphenyl ether, and the compatibility with the polymer is poor, so the processing fluidity and the physical and mechanical properties of the product are poor. In addition, compared with decabDE, the cost rises higher.

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