Threaded container closure

Abstract

The present invention is directed to a closure having a top wall which has a base cross-sectional thickness, a threaded portion and an annular skirt depending therefrom which includes tamper-evident means frangibly connected thereto. The top wall further comprises a stiffening block from which an inner annular seal and an outer annular seal depend. The inner annular seal is characterized by depending from a point of the stiffening block which is midway between the inner and outer periphery of the stiffening block and which is positioned to sealingly engage the inner wall of the opening of a container to which the closure is applied. The outer annular seal depends from the stiffening block in a manner such that the outer wall of the seal defines the outer periphery of the stiffening block. The stiffening block contains also a groove which defines the point of attachment of the inner wall of the outer seal and the sealing block and a step between the inner and outer seal which impinges the opening of a container to which the closure is affixed. This arrangement provides improved sealing and decoupling of stresses placed on the closure top wall from the sealing means.

1 . A closure having a cross-section of the closure in  FIG. 1  containing a plug sealing arrangement which engages the internal wall of a container opening upon application of the closure to the container, and which has a outer-lip sealing means that engages the outer-lip of the container opening upon application of the closure to the container.  
   
   
       2 . The closure of  claim 1  wherein said inner and outer sealing means disengage from the container prior to said threaded portion disengaging from the container.  
   
   
       3 . A container closure having a top wall which has a base cross-sectional thickness and depending from the periphery thereof, an annular skirt having an internally threaded portion and frangibly attached to the free edge of said annular skirt, a tamper-evident means which includes means for engaging a feature on a container to which the closure is applied to facilitate separating said tamper-evident means from said annular skirt at said frangible connection, and wherein the closure is further characterized by: 
 a. a filled shoulder region between said top wall and said annular skirt forming a substantially conical profile having a face oriented toward the radial axis of the closure;    b. depending from said top wall and centered on the radial axis of the closure, an annular sealing means comprising: 
 (i) a stiffening block depending from said top wall coaxially with said annular skirt in the form of a ring of material having an inner and outer periphery which is characterized in having a cross-section thicker than said top wall base thickness;  
 (ii) an annular outer seal depending from the stiffening block proximal to said closure shoulder, having an outer wall defining the outer periphery of said stiffening block and an inner wall facing the radial axis of the closure, and which is further characterized in having at least a portion of the free end thereof which projects toward said annular skirt;  
 (iii) an annular inner seal having an inner and an outer wall depending from said stiffening block, said inner wall defining a point of attachment to the stiffening block at a point outboard of the edge of the inner periphery of said stiffening block, said outer wall defining a point of attachment to the stiffening block inboard of said inner wall of the annular outer seal, the inner seal being further characterized in projecting toward said annular skirt, and wherein said annular inner seal has a face directed toward the radial axis of the closure which is substantially conical and is further characterized by the outer wall defining a surface having an outermost diameter greater than the opening of a container to which the closure is applied which enters into sealing engagement with the opening of said container; and  
 (iv) an annular groove in said stiffening block which defines the point of attachment of the inner wall of said outer seal with said stiffening block and which is further characterized by having a depth yielding a cross-sectional thickness to the stiffening block which is at least as great as the base thickness of the closure top wall and which is disposed in the stiffening block to provide a step between the point of attachment of the outer wall of said inner annular seal to said stiffening block and said groove, said step being positioned to impinge a portion of the inner edge of the opening of a container to which the closure is attached,  
 wherein the diameter and length of said inner and outer seal and the spacing between them are selected to accommodate a container opening and place said outer seal in a biaxial stretching condition against the lip of the container opening.  
   
   
   
       4 . The closure of  claim 3  wherein the base thickness of the top wall, and the cross-sectional thickness of the stiffening block and annular groove are selected such that doming of the cap due to stress is confined to the central region of the cap within the inner periphery of said stiffening block.  
   
   
       5 . A package comprising a container assembled with a closure of  claims 1  to  4 .