Helical lock closure system

Abstract

A container-closure assembly comprising a cap of cup-like form having a circumferentially expending skirt and a circumferentially extending flange depending from the top and spaced radially inwardly from the skirt and a series of radially inwardly directed circumferentially re-spaced lugs on the inner periphery of the skirt, the container having a neck portion with a discharge opening, the outer peripheral surface of the container being tapered upwardly and inwardly whereby the flexible flange engages the tapered surface when the cap is positioned over the container means defining a series of circumferentially re-spaced hook portions only on the container neck including a downwardly facing notched recess and a tapered face, said lugs position below a plain through the tip of the taper only hooks when the flexible flange lightly engages the tapered finish on the neck of the container.

What is claimed is:  
     
         1 . A container-closure assembly comprising a cap of cup-like form having a circumferentially expending skirt and a circumferentially extending flange depending from the top and spaced radially inwardly from the skirt and a series of radially inwardly directed circumferentially spaced lugs on the inner periphery of the skirt, the container having a neck portion with a discharge opening, the outer peripheral surface of the container adjacent said discharge opening being tapered upwardly and inwardly whereby the flexible flange engages the tapered surface when the cap is positioned over the container, means defining a series of circumferentially extending, spaced hook portions on the container neck having a downwardly facing notched recess and a tapered face, said lugs positioned below a plane through the tip of the taper on the hooks when the flexible flange lightly engages the tapered finish on the neck of the container.  
     
     
         2 . A container-closure assembly as claimed in  claim 1  wherein at least the inter-engaging surfaces of the flexible flange and the beveled container finish are of different plastic materials.  
     
     
         3 . A container-closure assembly as claimed in  claim 2  wherein one of said inter-engaging surfaces is propylene and the other surface is polyethylene.  
     
     
         4 . A container-closure assembly as claimed in  claim 3  wherein the hook elements have a downwardly tapered cam surface and wherein the lugs are disposed below a plane transverse to the axis of the container extending through the highest point on the cam surfaces so that the cap only has to be rotated to engage the lugs into the locking slots to secure the cap to the container.