Method of forming a container having a low crystallinity
AssigneeContinental PET Technologies, Inc.
InventorsWayne N. Collette, Suppayan M. Krishnakumar, Chih C. Lin
Life of this patent
Estimating the term…
Abstract
A plastic container, particularly suited for returnable and refillable PET carbonated beverage bottles, having an enhanced level of crystallinity in the sidewall but maintaining a very low level of crystallinity in the base. The container can withstand higher caustic wash temperatures and exhibits reduced flavor carryover from one product to another. The container is formed from a preform, wherein a sidewall-forming section of the preform is initially expanded and then heated to contract and crystallize the same before being reexpanded, and a base-forming portion of the preform is shielded from the heat treatment and expanded either before or after the heat treatment.
Claims49
A method of making a container having a sidewall and base comprising the steps of:
- providing a substantially amorphous polyester preform having a sidewall-forming section and a base-forming section, wherein the sidewall-forming section is within the orientation temperature range of the polyester;
- expanding the sidewall-forming section at least radially to form an intermediate article having an expanded intermediate sidewall with dimensions substantially equal to or greater than the dimensions of the final container sidewall, while the base-forming section remains substantially unchanged in dimensions;
- heating the expanded intermediate sidewall to crystallize and contract the same below the dimensions of the final container sidewall, while the base-forming section remains substantially amorphous and substantially unchanged in dimensions;
- and
- expanding the contracted intermediate sidewall and base-forming section while in the orientation temperature range to the final dimensions of the container sidewall and base.
A method of making a container having a sidewall and base comprising the steps of:
- providing a substantially amorphous polyethylene terephthalate preform having a sidewall-forming section and a base-forming section, wherein the sidewall-forming section is within the orientation temperature range of polyethylene terephthalate;
- expanding the sidewall-forming section axially and radially at a planar stretch ratio of about 10-16:1 to form an intermediate article having an expanded intermediate sidewall with dimension substantially equal to or greater than the dimensions of the final container sidewall, while the base-forming section remains substantially unchanged in dimensions;
- heating the expanded intermediate sidewall to crystallize and contract the same below the dimensions of the final container sidewall, while the base-forming section remains substantially amorphous and substantially unchanged in dimensions;
- and
- expanding the contracted intermediate sidewall and base-forming section while in the orientation temperature range to the final dimensions of the container sidewall and base, the contracted intermediate sidewall being stretched at a planar stretch ratio of about 7-15:1 (sidewall:sidewall-forming section) to form the sidewall having a wall thickness of about 0.5 to about 0.7 mm and a percent crystallinity of at least about 20%, and the base having a percent crystallinity of no greater than about 10%.
Dependencies are inferred from the claim text.