| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a two-layer preform which prevents the generation of breaking, lifting, whitening, protrusion, etc., in the preform and in the bottom part of the a bottle using the preform. SOLUTION: In the method for producing the two-layer preform 10 of polyethylene terephthalate, an outer layer shell 100 having a through hole 110 for a gate in the lower end bottom part is fitted in a mold for injection molding in advance, and an inner layer shell 200 is injection-molded integrally on the inside of the outer layer shell. The range of the diameter R of the bottom part through hole of the outer shell and the range of the wall thickness D of the bottom part are provided by the intrinsic viscosity of the polyethylene terephthalate of the inner layer shell. |
