Process for making plastic closures and closure

Abstract

A process for realizing plastic capsules ( 1 ) comprises: a first forming stage for realizing a cap ( 2 ) having an internal annular projection ( 2 a ) arranged in proximity of an open lower zone of the cap ( 2 ); a second forming stage of an annular element ( 3 ), provided with a security element ( 4 ) and with an external annular projection ( 3 a ) for inserting, during an assembly stage of the cap ( 2 ) with the annular element ( 3 ), over the internal annular projection of the cap ( 2 ). A stage of mechanical working is performed on the cap ( 2 ), for realizing, on an internal wall of the cap ( 2 ) and in proximity of a lower zone thereof, an annular incision ( 2 b ) which does not pass entirely through the cap ( 2 ) and which receives at least a part of the external annular projection ( 3 a )

1 . A process for realising capsules ( 1 ) made of plastic, comprising: a first forming stage for realising a cap ( 2 ), which cap ( 2 ) is destined to enable opening and re-closing of a container to which the cap ( 2 ) will be applied, which cap ( 2 ) is provided with an internal annular projection ( 2   a ) arranged in proximity of an open lower zone of the cap ( 2 ); a second stage of forming to realise an annular element ( 3 ), provided with a security element ( 4 ), connected to the annular element ( 3 ) by easy-break zones, and further provided with an external annular projection ( 3   a ) for inserting, during an assembly stage of the cap ( 2 ) with the annular element ( 3 ), over the internal annular projection of the cap ( 2 ); wherein after the first forming stage and before the assembly stage of the cap ( 2 ) with the annular element ( 3 ), a stage of mechanical working is performed on the cap ( 2 ), for realising, on an internal wall of the cap ( 2 ) and in proximity of a lower zone thereof, an annular incision ( 2   b ) which does not pass entirely through the cap ( 2 ) and which, during the assembly stage of the cap ( 2 ) with the annular element ( 3 ), receives at least a part of the external annular projection ( 3   a ) of the annular element ( 3 ). 
   
   
       2 . The process of  claim 1 , wherein the stage of mechanical working is performed in such a way that a zone of the cap ( 2 ) in which the incision ( 2   b ) is made maintains a resistance to breakage which is higher than a resistance to breakage of all of the easy-break zones which connect the security element ( 4 ) to the annular element ( 3 ). 
   
   
       3 . The process of  claim 1 , wherein the mechanical working stage comprises a stage of cutting performed by blades having shaped cutting edges. 
   
   
       4 . The process of  claim 3 , wherein the cutting stage is performed by insertion of one or more blades into the cap ( 2 ) wall, entering the cap ( 2 ) from the open end thereof and cutting in a direction which is a radial direction of the cap ( 2 ). 
   
   
       5 . The process of  claim 1 , wherein it comprises a stage of aspiration of portions of cap ( 2 ) which become detached from the cap ( 2 ) during the mechanical working stage. 
   
   
       6 . The process of  claim 1 , wherein the first forming stage is a stage comprising compression forming. 
   
   
       7 . The process of  claim 1 , wherein the stage of mechanical working is performed after heating the cap ( 2 ). 
   
   
       8 . The process of  claim 7 , wherein during the stage of mechanical working at least the lower part of the cap ( 2 ) is closed between a pair of jaws which are heated to a temperature comprised between 40° C. and 60° C. 
   
   
       9 . A capsule made according to the process of  claim 1 , comprising: a cap ( 2 ) destined to enable opening and re-closing of a container to which the cap ( 2 ) is to be assembled, which capsule is provided with an internal annular projection ( 2   a ) arranged in proximity of the lower open zone of the cap ( 2 ); an annular element ( 3 ), provided with a security element ( 4 ) connected to the annular element ( 3 ) by easy-break zones, and provided with an external annular projection ( 3   a ) which inserts, during the assembly stage of the cap ( 2 ) to the annular element ( 3 ), over the internal annular projection ( 2   a ) of the cap ( 2 ); wherein the cap ( 2 ) comprises, in an internal wall thereof in proximity of a lower zone thereof, an annular incision ( 2   b ) which does not pass entirely through the wall of the cap ( 2 ) and which is destined at least partially to receive the external annular projection ( 3   a ) of the annular element ( 3 ) during the assembly of the cap ( 2 ) with the annular element ( 3 ). 
   
   
       10 . The capsule of  claim 9 , wherein the zone of the cap ( 2 ) affording the incision ( 2   b ) exhibits a resistance to breakage which is higher than a resistance to breakage of the easy-break zones which connect the security element ( 4 ) to the annular element ( 3 ). 
   
   
       11 . The capsule of  claim 9 , wherein the incision ( 2   b ) is arranged above the internal annular projection ( 2   a ) with respect to the open lower zone of the cap ( 2 ).