Patent ID: 6090334
Filing Date: 2000-07-18
Classification: B29B,B29C,B29K,B29L,B65D,Y10S

Abstract:
A method of producing a heat resistant and pressure resistant self-standing container in which the bottom portion includes a plurality of foot portions and valley portions, said valley portions forming part of a substantially semispherical surface, by blow-molding a cylindrical preform with bottom that is heated at a drawing temperature, said method comprising:a step for subjecting a preform to a biaxial stretch-blow-molding in a metal mold to obtain a secondary article in which a portion that should serve as the bottom portion of the final container has a surface area larger than the surface area of said semispherical surface, said secondary article further having a dome-shaped bottom portion of which thickness is reduced to not larger than 1 mm by the biaxial stretch-blow-molding except the center of the bottom portion and of which degree of crystallinity is not smaller than 20% except the center of the bottom portion;a step of exposing the bottom portion of said secondary article and part of the barrel portion continuous to the bottom portion to infrared-ray radiation and heat-shrinking the exposed portions in order to obtain a tertiary article in which the portion should serve as the bottom portion of the final container has a size that can be accommodated in said semispherical surface, and has a shape close to that of the semispherical surface; anda step for secondarily blow-molding said tertiary article in a heated state in a metal mold in order to obtain the final container.