Tamper evident closures for containers

Abstract

A cap ( 10 ) including a transverse end wall ( 12 ) and a skirt ( 14 ) is disclosed. The skirt ( 14 ) is divided by a line of weakening ( 24, 26 ) into a main part ( 22 ) and a band ( 20 ). At least the band ( 20 ) is of heat shrinkable material. When the band is heated after fitting to the container ( 18 ) it pulls in under a bead ( 36 ) which encircles the container's neck.

1 . A method of manufacturing a cap for closing a container, the method comprising moulding the cap with a skirt which is subdivided by a circumferentially extending line of weakening into a main part and a band, at least the band being of heat shrinkable material.  
   
   
       2 . A method as claimed in  claim 1  and including the step of expanding the moulded band thereby to increase its diameter.  
   
   
       3 . A method as claimed in  claim 2 , wherein the band is expanded mechanically by means of movable components of the mould.  
   
   
       4 . A method as claimed in  claim 2 , wherein the band is subjected to air pressure to expand it.  
   
   
       5 . A cap which comprises a transverse end wall and a cylindrical skirt, an end portion of the skirt being in the form of a band which is connected to the main part of the skirt along a line of weakening, the band being of heat shrinkable material.  
   
   
       6 . A method of closing a container which comprises fitting a cap as claimed in  claim 5  to the container, and subjecting the band to heating to shrink it onto the container.  
   
   
       7 . A tamper evident cap which comprises a transverse end wall and a cylindrical skirt, the end portion of the skirt being in the form of a band joined to the remainder of the skirt by a series of bridges, the band having been stretched during manufacture and being of a material which shrinks when it is heated.  
   
   
       8 . A tool for use in the manufacture of a tamper evident cap, the tool comprising a female mould and a mandrel which together define a mould cavity having the shape of the cap to be moulded, the mould cavity having a first part in which the greater part of the length of the skirt of the cap and a transverse end wall of the cap are moulded, a second part in which a band forming the end part of the skirt of the cap is moulded, and notches arranged in a circle, the notches joining the cavity parts and a series of bridges between the band and the remainder of the skirt being moulded in these notches, the inner diameter of at least a portion of the subsidiary cavity part being less than the inner diameter of at least a portion of the main cavity part.  
   
   
       9 . A method of moulding a cap which comprises feeding synthetic plastics material to a mould cavity defined between surfaces of a mandrel and surfaces of a female mould, the mould cavity having the shape of the cap to be moulded, the mould cavity having a first part in which the greater part of the length of a skirt of the cap and a transverse end wall of the cap are moulded, a second part in which a band forming the end part of the skirt is moulded, and notches arranged in a circle and which join the cavity parts, the inner diameter of at least a portion of the subsidiary cavity part being less than the inner diameter of at least a portion of the main cavity part, and removing the moulded cap from the mandrel in such manner that the band is stretched as it passes over the part of the mandrel which defines the first part of the mould cavity.