Cationic polyester: the main raw materials are terephthalic acid, ethylene glycol monomer, by adding 1~2 kinds of special 3rd or 4th monomers for copolymerization to enhance the dyeing ability.

Water-soluble polyester: The main raw materials are terephthalic acid, ethylene glycol monomer, by adding 1~2 kinds of special 3rd or 4th monomers to lower the melting point, enhance the hydrophilic function.

Low-melting-point polyester: The main raw materials are terephthalic acid and ethylene glycol monomers. By introducing 3rd and 4th monomers for modification, the proportion of modification determines the variation in low-melting-point grades.

Flame-retardant polyester: The main raw materials are terephthalic acid and ethylene glycol monomers. Flame retardancy is achieved by adding a phosphorus-containing 3rd monomer for copolymerization.

Two different kinds of process: Batch process and continuous process. Batch process mainly includes single-reactor system, double-reactor system, and three-reactor system, etc.; Continuous process mainly includes four-reactor process and five-reactor process. For some varieties, special functional reactor units need to be equipped. Usually, a multifunctional reactor with a special structure can realize flexible production of multiple varieties PET.