Around 400 yuan, polyester fiber is a synthetic fiber spun from polyester condensed by organic diacid and diol. Polyester fiber produced in large quantities in industry is made of polyethylene terephthalate, and the trade name of China is polyester. It is the largest variety of synthetic fibers at present. Regenerated fibers are mainly divided into two categories: regenerated cellulose fibers and regenerated synthetic fibers. Viscose fiber is the earliest regenerated fiber, and then new regenerated cellulose fibers such as lyocell fiber, cellulose carbamate fiber, superconducting viscose fiber, kapok fiber and bamboo fiber appeared one after another. Polyester fiber accounts for about 70% of synthetic fiber, and the application of polyester in bottle-making industry is expanding rapidly, so recycled synthetic fiber is mainly recycled polyester fiber.