Closure with improved resistance to deformation during opening

Abstract

A plastic closure for a container includes a top wall and a downwardly depending substantially cylindrical skirt that is unitary with the top wall. The skirt defines inner and outer surfaces as well as a lower rim at a distal, bottom end thereof. In addition, at least one thread is defined on the inner surface of the skirt. Most advantageously, reinforcing structure is provided on the skirt an area between the lower rim and a lowermost thread of the inner surface for enhancing the dimensional integrity of the closure during opening.

1 . A plastic closure for a container, comprising: 
 a top wall;    a downwardly depending substantially cylindrical skirt that is unitary with said top wall, said skirt defining inner and outer surfaces and further defining a lower rim at a distal, bottom end thereof;    at least one thread that is defined on said inner surface of said skirt; and    reinforcing means defined on said skirt in an area between said lower rim and a lowermost thread on said inner surface for enhancing the dimensional integrity of the closure during opening.    
   
   
       2 . A plastic closure according to  claim 1 , wherein said reinforcing means comprises an area of increased skirt thickness in an area between said lower rim and a lowermost thread on said inner surface that is at least 0.05 inches in maximum thickness.  
   
   
       3 . A plastic closure according to  claim 2 , wherein said reinforcing means comprises an area of increased skirt thickness in an area between said lower rim and a lowermost thread on said inner surface that is at least 0.06 inches in maximum thickness.  
   
   
       4 . A plastic closure according to  claim 3 , wherein said reinforcing means comprises an area of increased skirt thickness in an area between said lower rim and a lowermost thread on said inner surface that is at least 0.07 inches in maximum thickness.  
   
   
       5 . A plastic closure according to  claim 1 , wherein said reinforcing means comprises an area of increased skirt thickness in an area between said lower rim and a lowermost thread on said inner surface, and said substantially cylindrical skirt has an outer diameter, and wherein a ratio of said thickness to said outer diameter is at least about 0.04.  
   
   
       6 . A plastic closure according to  claim 5 , wherein said ratio is at least 0.05.  
   
   
       7 . A plastic closure according to  claim 1 , further comprising a tamper-evident band frangibly connected to said lower rim.  
   
   
       8 . A plastic closure according to  claim 1 , wherein said reinforcing means comprises an area of increased skirt thickness in an area between said lower rim and a lowermost thread on said inner surface, and wherein a product of said thickness and a vertical distance between said lower rim and a lowermost thread on said inner surface is at least 0.0040.  
   
   
       9 . A plastic closure according to  claim 8 , wherein said product is at least 0.0045.  
   
   
       10 . A plastic closure according to  claim 9 , wherein said product is at least 0.0048.  
   
   
       11 . A plastic closure according to  claim 1 , wherein said reinforcing means comprises an area of increased skirt thickness in an area between said lower rim and a lowermost thread on said inner surface, and wherein said area of increased skirt thickness is shaped to define a substantially smooth inner surface.  
   
   
       12 . A plastic closure according to  claim 11 , wherein said inner surface of said area of increased skirt thickness is substantially cylindrical in shape.