Polyamide plastic is developed on the basis of poly (phthalamide) fiber. It is the first thermoplastics that can bear the load. It is also the variety with the largest output, the largest variety and the widest use among the five general engineering plastics. PA is a kind of general engineering plastics with a long history and wide application. In 2000, the market distribution of world engineering plastics was PA 35%, PC 32%, POM 11%, PBT 10%, PPO 3%, pet 2%, UHMWPE 2%, and high performance engineering plastics (PPS, LCP, peek, Pei, PESU, PVDF, other fluoroplastics, etc.) 2%. Due to the rapid growth of PC market demand, its market share has exceeded that of PA.

Polyamide resin, the English name is polyamide, referred to as PA. Nylon, commonly known as nylon, is one of the five engineering plastics with the largest output, the largest variety and the widest use. The main varieties of nylon are nylon 6 and nylon 66, which are dominant. Nylon 6 is polycaprolactam, while nylon 66 is polyhexanediamine adipate. Nylon 66 is 12% harder than nylon 6; The second is nylon 11, nylon 12, nylon 610, nylon 612, as well as nylon 1010, nylon 46, nylon 7, nylon 9, nylon 13. New varieties include nylon 6I, nylon 9t, and special nylon MXD6 (barrier resin). There are many kinds of nylon modification, such as reinforced nylon, monomer casting nylon (MC nylon), reaction injection molding (RIM) nylon, aromatic nylon, epoxy resin, etc Transparent nylon, high impact (super tough) nylon, electroplated nylon, conductive nylon, flame retardant nylon, nylon and other polymer blends and alloys meet different special requirements, and are widely used as substitutes for metal, wood and other traditional materials.

Considering the performance and price, the market consumption of PA6 and PA66 still accounts for about 90% of the total amount of PA, occupying a leading position. In 2001, the world consumption of PA66 was 740000 tons, slightly higher than 680000 tons of PA6. In Europe, PA6 accounts for 50%, PA66 accounts for 40%, PA11, PA12 and other homopolymers and copolymers account for 10%. The consumption of PA66 in the United States exceeds that of other varieties. In Japan, PA6 accounts for 52%, PA66 38%, PA11 and PA12 5%, PA46 and semi aromatic PA 5%. PA engineering plastics are mainly injection molded, and injection molded products account for about 90% of PA products. The molding processes of PA6 and PA66 are not the same. PA66 basically adopts injection molding, accounting for 95%, and extrusion molding only accounts for 5%; The injection molding products of PA6 account for 70%, and extrusion molding accounts for 30%.