Tamper-proof bottle cap

Abstract

The invention relates to a tamper-indicating bottle closure consisting of a threaded bottle cap and a tamper-indicating band connected thereto by selectively rupturable connectors. The band is provided with at least to radially protruding camming members adapted to move over a retaining lip provided on a bottle, by temporarily radially deforming the band, during closure movement between cap and bottle and to be locked behind the retaining rib during opening movement between cap and bottle at a force exceeding the force of the opening movement.

What is claimed is:  
     
         1 . A threaded tamper-proof bottle closure for use with a bottle provided with an opening a neck provided with thread and a retaining lip on the side of the thread opposite the opening, comprising: 
 a cap having a base portion and a skirt extending angularly therefrom and provided with threads adapted to mate with the thread on the neck to impart opening and closing axial movement therebetween during relative rotational movement thereof;    an annular tamper-indicating band extending axially of the skirt and provided with at least a first pair of unitary camming members disposed opposite each other in a first axial plane and a second unitary camming member angularly displaced from the first pair and disposed in a second axial plane, the camming members being adapted by radial deformation of the band sequentially to move over the retaining rib during rotational closure movement between the cap and the bottle and to move into locking engagement with the retaining rib during rotational opening movement between the cap and the bottle; and    means for releasably connecting the band to the skirt, the means being of a strength exceeding the torque required for moving the camming members over the retaining rib and sufficiently weak to rupture by engagement of at least one of the camming members with the retaining rib during opening rotational movement between the cap and the bottle.    
     
     
         2 . The closure of    claim 1   , wherein there are provided at least two pairs of oppositely placed camming members disposed in axially separated planes.  
     
     
         3 . The closure of    claim 2   , wherein the retaining rib is of a predetermined axial dimension and the first and second axial planes are separated from each other by less than the axial dimension.  
     
     
         4 . The closure of    claim 2   , wherein the connecting means comprises a plurality of rupturable strands extending between a lower margin of the cap and an upper margin of the band.  
     
     
         5 . The closure of    claim 4   , wherein the strands are alternatingly positioned between the camming members.  
     
     
         6 . The closure of    claim 1   , wherein the connecting means comprised a circumferential section permanently connecting the cap and the band and a plurality of selectively rupturable strands and wherein the band is provided with a selectively rupturable section.  
     
     
         7 . The closure of    claim 6   , wherein one camming member is positioned diagonally opposite the rupturable section.  
     
     
         8 . The closure of    claim 1   , wherein the retaining rib and the camming members are provided with complementary inclined surfaces to facilitate movement of the camming members over the retaining lip.  
     
     
         9 . The closure of    claim 1   , wherein the cap, band and connecting means are integrally formed.  
     
     
         10 . The closure of    claim 1   , wherein the cap, band and connecting means are made of a thermoplastic material.