Due to the high oxygen index of PA66 resin and certain flammability, its application in various fields has been restricted. In order to increase the application scope of PA66 engineering plastics, its flame retardant properties should be further improved. There are many domestic researches on the flame retardant modification of nylon 66. Among them, adding flame retardant to PA66 resin is a very common way to improve the flame retardancy of PA66 engineering plastics, and the effect of this manufacturing method is very significant.

There are two ways to improve the flame retardancy of PA66 engineering plastics: one is to use increased flame retardants, and the other is to use reactive flame retardants. The increased flame retardant is added to the PA66 resin, and then mechanical blending is used to fuse the two. Physically dispersing the flame retardant in the PA66 resin matrix is ??the primary method of flame retardant modification. The advantages of this method are convenience, wide applicability and significant modification effect. According to people’s experience in the manufacture of PA66 engineering plastics, commonly used increased flame retardants include phosphorus flame retardants, nitrogen flame retardants, halogen flame retardants, inorganic flame retardants and so on.

Two methods for the flame retardant modification of PA66 engineering plastics are to combine flame retardants as reactive monomers to the PA66 macromolecular chain to make them the flame retardant components in the PA66 structural unit. The advantages of this modification method are good stability, long-lasting flame retardant effect and little impact on other properties of the material, and it will not present flame retardant evaporation and migration problems; but this method has the complex processing technology and high modification cost. Defects are subject to certain constraints in the actual production and manufacture of PA66 engineering plastics. The commonly used reactive flame retardants are mainly phosphorus-containing polyols and halogenated acid anhydrides, such as bis(4-carboxyphenyl)phenyl phosphorus oxide and bis(hydroxyethyl)methyl phosphine oxide.