open ended container closure including a flexible membrane and a rigid cap

Abstract

The invention concerns a closure for a cylindrical can ( 10 ) The closure includes a flexible member ( 11 ) of the easy-open type secured across the open end of the can ( 10 ). A rigid, screw cap ( 22 ) is screwed over the thus sealed end of the can. An annular, resilient member ( 24 ) depending downwardly from the underside of the end wall of the cap ( 22 ), engages the membrane ( 11 ) in the vicinity of the end flange ( 18 ) of the can body ( 10 ) thereby strengthening the seal between the membrane ( 11 ) and the flange ( 18 ). This advantageously permits cooking of the contents of the can with the flexible membrane ( 11 ) in situ, thereby giving rise to a can having an easy-open end, the contents of which can are cooked and sterilized using conventional processing lines.

1 . A method of closing an open-ended container with a closure to form a container assembly comprising the steps of: 
 (i) providing a flexible membrane for closing the open end of the container;    (ii) providing an adhesive seal between the flexible membrane and the container; and    (iii) providing a rigid cap having a resiliently deformable member juxtaposed to the flexible membrane such that when the cap is in use, the flexible membrane is pressed against the container in the vicinity of the seal, thereby reinforcing the seal sufficiently to withstand high pressures which are generated from cooking the contents of the container; 
 the rigid cap further having a first cam and follower pair, which when in use is engaged with a second cam and follower pair located on a container neck, relative movement between the first and second cam and follower pairs in a predetermined direction causes the rigid cap and the container neck to approach one another, thereby increasing the pressure exerted by the resiliently deformable member on the flexible membrane; and  
 the rigid cap further having a laminar member and an annular skirt, the skirt extending downwardly from the laminar member, and the second cam and follower pair is secured on an upper wall of the skirt,  
 wherein the laminar member is spaced from the flexible membrane by a distance less than the maximum possible extension of the flexible membrane towards the laminar member.  
   
   
   
       2 . The method according to  claim 1  comprising the steps of: 
 (i) adhesively securing said flexible membrane on the open end of the container neck, thereby forming said seal;    (ii) engaging the first cam and follower pair of the rigid cap and the second cam and follower pair of the container neck with one another; and    (iii) moving the rigid cap and the container neck relative to one another to cause relative movement between the first and second cam and follower pairs in the predetermined direction, thereby causing the resiliently deformable member to press the flexible membrane against the container in the vicinity of the seal sufficiently to maintain the seal against pressures generated in the container on cooking of its contents.    
   
   
       3 . The method according to  claim 2  including the step of securing the flexible membrane on the open end of the container neck by use of a heat-sealing method such as heat contact, ultrasonic, induction or hot air heating.  
   
   
       4 . The method according to  claim 2  wherein the step of moving the rigid cap and the container neck relative to one another includes rotating the rigid cap and the container relative to one another.  
   
   
       5 . The method according to  claim 2  wherein the step of adhesively securing the flexible membrane on the open end of the container neck further includes the sub steps of applying adhesive material to the flexible membrane and/or the container neck; engaging the flexible membrane and the container neck with one another to define the seal; and curing the adhesive material.  
   
   
       6 . The method according to  claim 5  wherein the substep of curing the adhesive material includes heating thereof.  
   
   
       7 . The method according to  claim 2  including the steps of: 
 adding food to the container through a second open end of the container which is opposite said open end closed by said closure;    closing said second open end by a conventional can end;    heating said food within said container to cook said food; and    preventing rupture of said flexible membrane due to internal container pressure caused by said heating by the presence of said laminar member of said cap.