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Container-closure assembly including a screw-cap having anti-backoff teeth on its threads

  • US 5,169,033 A
  • Filed: 11/13/1991
  • Issued: 12/08/1992
  • Est. Priority Date: 11/13/1991
  • Status: Expired due to Term
First Claim
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1. A container-closure assembly comprising(a) a container molded of a relatively soft plastic and having an integral finish formed with outward screw threads extending thereabout, and(b) a closure molded of a relatively hard plastic and comprising at least a partial top wall and a continuous side wall having inward threads extending thereabout adapted to threadedly receive the threads on the finish, the threads on the cap comprising a plurality of thread segments uniformly spaced about the inner circumference of the side wall, the segments comprising an inward rib having a sloping upper surface generally perpendicular to the sidewall and having spaced therealong a plurality of inclined wedge-shaped teeth, each having a front face sloping upward in the same direction as the rib and at a slightly greater angle and a generally vertical abrupt rear face descending down to said inward rib, the upper surface and the front face defining a point,whereby when the closure is screwed tightly onto the finish, the points of the teeth dig into the underside of the outward screw threads of the finish to cause the instantaneous elastic deformation of the contiguous plastic of the finish to surround the point and resist the backing off of the closure from the finish.

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