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Method of making a molded plastic container

  • US 5,730,914 A
  • Filed: 01/16/1996
  • Issued: 03/24/1998
  • Est. Priority Date: 03/27/1995
  • Status: Expired due to Fees
First Claim
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1. A method of making a molded plastic container from a preform made from polyethylene terephthalate, comprising the following steps:

  • a. preheating to soften the preform;

    b. inserting the preform into a split mold whose walls are heated to a temperature in the range of 130°

    C. to 240°

    C.;

    c. inserting a stuffer into the preform;

    d. injecting a first gas into the preform, thereby expanding and molding the preform against the walls of the mold, and holding pressure in the molded preform for a predetermined time;

    e. venting the first gas from the molded preform;

    f. while venting, injecting vaporized nitrogen into the molded preform at a pressure of at least about 2070 kPa, the vaporized nitrogen entering the interior of the preform at a temperature below -100°

    C., and purging and cooling the molded preform with the vaporized nitrogen for a predetermined time, during which time the molded preform transforms into a final product; and

    g. releasing the final product from the mold.

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