Virgin polyester staple fiber is primarily produced using melt spinning, where the polyester melt is directly spun and cut. The raw materials for synthetic polyester are poly(terephthalic acid) and ethylene glycol, mainly obtained from petroleum cracking. Polyester melt can be obtained by transesterification and polycondensation of dimethyl terephthalate and ethylene glycol, or by direct esterification and polycondensation of terephthalic acid and ethylene glycol.
Recycled polyester staple fiber is mainly derived from waste pulp and waste yarn from chemical fiber production, garment printing and dyeing scraps, and recycled PET bottles. During staple fiber spinning, polyester chips are dried, melted, and then spun. Multiple strands are gathered, moistened, oiled, and fed into a yarn container. The finished product is then obtained through processes such as bundling, stretching, crimping, heat setting, and cutting. If a tense heat setting at approximately 180°C is applied after stretching, high-strength, low-elongation staple fiber can be obtained. Solution dyeing technology can be used to reduce material residue in the fiber dyeing process. Composite structure design can be used to improve the fiber's flexibility and adsorption properties.
