Sealing of a cap on a glass container
A multi-layer sheet designed for the sealing of a container ( 10 ) made of glass by heat sealing on the sealing ring ( 12 ) of the container treated by means of oxides and/or of metal salts comprises at least a support layer ( 21 ) and a lower layer ( 22 ) made of a polymeric heat-sealable material onto which is grafted an unsaturated carboxylic acid.
1. Composite packaging comprising a glass container and a heat-sealable closer sealed onto a sealing ring of a glass container, wherein the sealing ring of the container is covered with a coating comprising oxides and/or metal salts, and in that said closer comprises at least one support layer and a lower layer made of a polymeric heat-sealable material onto which is grafted an unsaturated carboxylic acid, said polymeric heat-sealable material having a melting point higher than 115° C.
2. Composite packaging according to claim 1 , wherein the packaging is sterilized at a sterilization temperature T st , wherein said polymeric heat-sealable material has a melting point higher than said sterilization temperature T st .
3. Composite packaging according to claim 1 , wherein said polymeric heat-sealable material is polypropylene homo or copolymer, high density polyethylene or polyester.
4. Composite packaging according to claim 1 , wherein the unsaturated carboxylic acid is maleic anhydride.
5. Composite packaging according to claim 1 , wherein the mass ratio of said unsaturated carboxylic acid to said polymeric material is lower than 2%.
6. Composite packaging according to claim 1 , wherein the mass ratio of said unsaturated carboxylic acid to said polymeric material is lower than 1%.
7. Composite packaging according to claim 1 , wherein said coating comprises a member selected from the group consisting of chromium salts, silanes, aluminum salts, and zirconium salts.
8. Composite packaging according to claim 1 , comprising a lid designed to be screwed on the container.
9. Packaging according to claim 8 , wherein the lid is made of plastic or metal.
10. Process for the manufacture of composite packaging according to claim 1 , comprising the steps of:
providing a glass container with a sealing ring covered with a coating comprising oxides and/or metal salts,
providing a closer comprising at least one support layer and a lower layer made of a polymeric heat-sealable material onto which is grafted an unsaturated carboxylic acid, said polymeric heat-sealable material having a melting point higher than 115° C.; and
heat-sealing said closer onto the sealing ring of the container.
11. Process according to claim 10 , also including, after the heat-sealing stage, a sterilization stage of the composite packaging.
12. Process according to claim 11 , wherein said sterilization stage comprises maintaining the composite packaging at a temperature ranging between 115 and 135° C. for a length of time ranging between 10 and 60 minutes.
13. Process according to claim 10 , additionally comprising the step of screwing a lid onto the container.