Polyamide fiber is the main varieties of nylon 66 and nylon 6. Nylon 66 has a melting point of 255-260 ° C, a softening point of about 220 ° C, a nylon 6 melting point of 215-220 ° C and a softening point of about 180 ° C. Both share the same weight (1.14) and are similar in many other properties, such as high strength, good resilience, highest wear resistance in textile fibers, resistance to multiple deformations and fatigue resistance close to polyester (see Polyester ), Higher than other chemical fibers, has good hygroscopicity, can be directly dyed with acid dyes and other dyes. The main disadvantages of nylon 66 and nylon 6 are poor light and heat resistance.
In 1939, DuPont developed polyamidite synthetic fiber named nylon, originally made of nylon 66, after the successful synthesis of nylon 6, suitable for forming the outside of the fiber to nylon 6 as the mainstream.
Japan Toray began production of polyamides nylon 6 in 1958 history than polyacetal and polycarbonate earlier, the EP needs the most widely used, the Japanese category is about PA6 accounted for 70%, 66% of 20%, other 10%.