INJECTION MOLDING METHOD FOR POLYETHYLENE TEREPHTHALATE

摘要

PROBLEM TO BE SOLVED: To prevent the generation of uneven wall thickness by adding crystalline polyethylene terephthalate to amorphous polyethylene terephthalate and increasing the TV value of a plasticized molding material above that of the amorphous polyethylene terephthalate. SOLUTION: The particles of A-PET and C-PET which are softened in a feed zone are melted, drawn, and mixed with each other by being compressed by the taper surface of a compression zone so that the TV value of the material as a whole is increased above that of A-PET only by the higher TV of C-PET. In this way, A-PET which is difficult to be kneaded due to its low TV value can be kneaded adequately to advance plasticization. The molten material is sent to the second stage 20 in which the temperature is set to be lower than that in the first stage 10.