Polyamide plastics are developed on the basis of the fiber of poly (phthalide), which is the first thermoplastic plastic to bear the load. It is also the most widely used and the largest production, variety and wide range of five general engineering plastics. PA is a general engineering plastics with a long history and wide application. In 2000, the world engineering plastics market was distributed to pa 35%, PC 32%, POM 11%, PBT 10%, PPO 3%, pet 2%, UHMWPE 2%, high performance engineering plastics (PPS, LCP, peek, Pei, PESU, PVDF, other fluoroplastics, etc.) 2%. As the demand of PC market grows rapidly, its market share has exceeded PA.

Polyamide resin, known as polyamide in English, is referred to as PA. Nylon is commonly known as nylon, which is the largest production, the most variety and the most widely used of five engineering plastics. Nylon 6 is mainly nylon 6 and nylon 66, which is the dominant one. Nylon 6 is polycaprolamide, while nylon 66 is adipate, nylon 66 is 12% harder than nylon 6; The next is nylon 11, nylon 12, nylon 610, nylon 612, and nylon 1010, nylon 46, nylon 7, nylon 9, nylon 13. New varieties include nylon 6I, nylon 9t and special nylon MXD6 (barrier resin), and so on. There are many kinds of nylon modification, such as reinforced nylon, monomer casting nylon (MC nylon), reaction injection molding (RIM) nylon, aromatic nylon Transparent nylon, high impact resistant (ultra 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 traditional materials such as metal and wood.

Considering the performance and price, the market consumption of PA6 and PA66 still accounts for about 90% of the total PA, which is the dominant position. In 2001, the consumption of PA66 in the world was 740000 tons, slightly higher than that of PA6. The consumption structure of PA6 in Europe is 50%, PA66 is 40%, PA11, PA12 and other homopolymerization and copolymerization PA account for 10%, the consumption of PA66 in the United States exceeds other varieties, while in Japan, PA6 is the first, 52%, PA66 accounts for 38%, PA11 and PA12 account for 5%, PA46 and semi aromatic PA account for 5%. The injection molding is the main part of PA engineering plastics, and the injection molding products account for about 90% of PA products. The molding process of PA6 and PA66 is different. PA66 is basically injection molding, accounting for 95% and extrusion molding only 5%; The injection molding products of PA6 accounted for 70% and extrusion molding accounted for 30%.