Method of forming container with high-crystallinity sidewall and low-crystallinity base
AssigneeContinental PET Technologies, Inc.
InventorsWayne N. Collette, Suppayan M. Krishnakumar, Chi Ching Lin
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Abstract
A method of making a polyester container having an enhanced level of crystallinity in the sidewall while maintaining a low level of crystallinity in a thickened base portion. The container is particularly useful as a refillable container which can withstand higher caustic wash temperatures and exhibits reduced flavor carryover, or as a hot-fill container. According to the method, a sidewall-forming section of a preform is initially expanded, heated to contract and crystallize the same, and than reexpanded; a base-forming portion of the preform is shielded from the heat treatment and is expanded either before or after the heat treatment step.
Claims13
A container comprising a substantially transparent, biaxially-oriented, free-standing, blow-molded polyester body, the body having a sidewall with an upper tapered shoulder and a substantially cylindrical panel and a footed base, the footed base having a thickened central base portion with a wall thickness at least about 3.times. greater than a thickness of the panel, the panel having an average crystallinity of at least about 25% and the thickened central base portion having an average crystallinity of no greater than about 2%, and the footed base further including a thinner base portion around the thickened central base portion with legs, ribs and feet, the thinner base portion having an average crystallinity of about 10 to 20%.
Dependencies are inferred from the claim text.