Process for injection molding polyethylene terephthalate

摘要

There is provided a process for injection molding a preform for stretch blow molding a thin-wall vessel such as a bottle using amorphous polyethylene terephthalate (A-PET) as a molding material, wherein a required amount of crystallized polyethylene terephthalate (C-PET) is added to the A-PET. The resulting mixture material can be easily plasticized to increase the IV value of the molding material to a value higher than that of A-PET so as to injection mold the preform. A-PET which is hardly usable as a molding material for stretch blow molding due to its low IV value is made usable as a molding material for stretch blow molding by increasing its IV value making use of plasticization at the time of injection molding.