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Process of uniformly expanding polymer film

  • US 5,512,229 A
  • Filed: 05/25/1994
  • Issued: 04/30/1996
  • Est. Priority Date: 11/17/1992
  • Status: Expired due to Term
First Claim
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1. A process for uniformly expanding a polymer film in multiple directions, the polymer film having a center, the process comprising in combination the steps of:

  • a. securing the periphery of the film to a plurality of symmetrically-disposed film gripping members, each of said film gripping members being equidistant from the center of the film;

    b. simultaneously rotating each of the plurality of film gripping members through an arcuate path defining an arc greater than zero degrees away from the center of the film to stretch and expand the film while maintaining said plurality of film gripping members equidistant from the center of the film; and

    c. maintaining the pulling force exerted by each film gripping member radial relative to the center of the film thereby forming a uniformly expanded polymer film.

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