| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for producing a PET resin bottle which can give excellent heat resistance and high strength to an underneck part as well as a neck part. SOLUTION: A preform 6 having a whitened/crystallized neck part 1, a barrel part 4, and a weakly whitened part 5 which is thinner than the barrel part 4 is heated to an orientation temperature. The preform is blow-molded, and the weakly whitened part 5 and the barrel part 4 are stretched in order to form a primary bottle 8. The primary bottle 8 is heated, the part 5 is softened, and a blow-molding part is shrunk freely. A secondary bottle 9 which is smaller than a final bottle form 7, has a recessed step parts on the inner and outer surfaces of the boundary part between the part 5 and a free shrinkage part, and is heated to the orientation temperature is formed. The secondary bottle 9 is blow-molded. The weakly whitened part 5 is stretched to eliminate the recessed step parts in order to form an underneck part 11. The free shrinkage part is stretched again in order to form a shoulder part, a barrel part 13, and a bottom part. The underneck part 11, the shoulder part 12, and the barrel part 13 are heat-set in order to mold a final bottle 15. The crystallinity of the oriented parts is at least 30%.</p> |
