The addition of flame retardants has a large impact on the mechanical properties of the product. Since most of the flame retardants are low molecular compounds, their compatibility with nylon is poor. Therefore, the addition of flame retardants will reduce the mechanical properties of nylon. With the increase of the amount of flame retardant, the impact strength and flexural strength of flame retardant PA6 and flame retardant PA66 show a downward trend. Whether the flame retardant is dispersed uniformly in flame retardant nylon has a certain effect on the flame retardant effect. Surface treatment can improve the adhesion and dispersibility between the flame retardant and the nylon substrate. It is beneficial to reduce the amount of flame retardants, which can reduce production costs and improve product mechanical properties. Red phosphorus is one of the halogen-free flame retardants that are widely used in nylon and polyester. It has the advantages of low addition and wide application. Ordinary red phosphorus is easy to absorb moisture, has poor compatibility with polymer materials, and is particularly liable to cause spontaneous combustion, which cannot be practically used. The microencapsulated red phosphorus flame retardant reduces the activity of red phosphorus and solves the compatibility. The content of red phosphorus is about 85%, but the problem of spontaneous combustion is not effectively solved, and the dust pollution is serious. The red phosphorus masterbatch is a dark red particle with red phosphorus mixed with inorganic flame retardants such as aluminum hydroxide and expanded graphite, and a matrix resin as a carrier. The safety problem has been solved. The flame retardant system has low smoke and high flame retardant efficiency; no dust pollution, and excellent processing performance; low density, good thermal stability, and reduced physical properties of the product; no frost, no migration, and no corrosion to the mold during processing.

Polymelamine phosphate (MPP) is another type of environmentally friendly flame retardant widely used in nylon flame retardants and polyester flame retardants. Its molecular chain structure is similar to that of APP. It is mainly used to replace side groups with melamine with a relatively large molecular weight. NH4 + therefore improves its thermal stability, but results in lower phosphorus content in MPP. It has been found through experiments that 25% MPP can only increase the oxygen index of glass fiber reinforced PA66 by 5.5%, and the vertical combustion performance is almost not improved. Therefore, it is necessary to add more MPP to flame retardant PA66, which results in the mechanical properties of the resin Severe decline. Melamine cyanurate (MCA) is also commonly used in nylon and polyester flame retardants. It is characterized by low toxicity, non-corrosion, and stability to heat and ultraviolet rays. However, its flame retardant nylon and polyester have strong melting drops when burning. It has poor flame retardancy to glass fiber reinforced nylon and polyester, can not reach UL94-V0 level, the product has poor electrical performance in humid environment, and has poor dispersibility in the base material, making it difficult to process.

According to different classification standards, nylon flame retardants can be divided into the following categories: 1. According to the contained flame retardant elements, the flame retardants can be divided into halogen flame retardants and phosphorus flame retardants. , Nylon flame retardants, phosphorus-halogen flame retardants, phosphorus-nitrogen flame retardants and other categories. Halogen flame retardants decompose X? And HX which capture and transfer combustion free radicals during pyrolysis. HX can dilute the combustible gas generated during the cracking of combustible materials and block the contact between combustible gas and air. Phosphorous flame retardants produce phosphoric anhydride or phosphoric acid during the combustion process, which promotes the dehydration and carbonization of combustibles and prevents or reduces the generation of combustible gases. Phosphoric acid anhydride also forms a glass-like melt on the surface of combustible materials during pyrolysis, which promotes its oxidation to form carbon dioxide and plays a flame retardant role.