Patent ID: 7833466

Claim:
A method of manufacturing a biaxially-oriented polyester container formed by a double-stage orientation blow molding method, the containers having a uniformly elongated bottom part having uniform wall thickness, the method comprising: (a) performing two-stage primary orientation blow molding of a preform made of a polyester resin to obtain a primary molded product larger than a final molded product, the two stages of primary orientation blow molding comprising: (i) a first stage, wherein the bottom part of the preform is elongated while being restrained by a stretch rod and a press rod to obtain an elongated preform; and (ii) a second stage, wherein the bottom part of the elongated preform is released from the restrained state prior to blow molding to provide the primary molded product; (b) heat-shrinking said primary molded product into a secondary molded product; and (c) performing secondary orientation blow molding of said secondary molded product to obtain the final molded product.