Two-piece container seal and method of manufacture
View Patent ↗An improved two-piece container seal suitable for sealing a container having a removable closure and for lining the closure comprises a flexible sealant sheet and a flexible liner sheet bonded thereto. The sealant sheet and liner sheet are of the same size and shape. The sealant sheet has a sealing surface and a first thermoplastic surface, and the liner sheet has an outer surface and a second thermoplastic surface. The first and second thermoplastic surfaces are in opposed, congruent contact with each other, and the first thermoplastic surface is ultrasonically welded to the second thermoplastic surface by an array of spaced, frangible ultrasonic welds, forming an adhesive-free interface therebetween. A method of manufacturing a two-piece container seal and a sealed container comprising a two-piece container seal are also described.
1. A two-piece container seal suitable for sealing a container having a removable closure and for lining the closure, the container seal comprising:
a flexible sealant sheet having a heat-sealable sealing surface and a first thermoplastic surface; and
a flexible liner sheet of the same size and shape as the sealant sheet, the liner sheet having an outer surface and a second thermoplastic surface;
the first and second thermoplastic surfaces being in opposed, congruent contact with each other, the first thermoplastic surface being ultrasonically welded to the second thermoplastic surface by an array of spaced, frangible ultrasonic welds, the interface between the first and second thermoplastic surfaces being adhesive-free.
2. The container seal of claim 1 wherein the liner sheet comprises a sheet of thermoplastic polymer.
3. The container seal of claim 1 wherein the total surface area of the frangible ultrasonic welds between the first and second thermoplastic surfaces encompasses less than about 5 percent of the surface area of each thermoplastic layer.
4. The container seal of claim 1 wherein the entire container seal is adhesive-free.
5. The container seal of claim 1 wherein the sealant sheet is a multilayer laminate and the first thermoplastic surface is a layer of thermoplastic polymer.
6. The container seal of claim 5 wherein the sealing surface of the sealant sheet is a layer of heat-sealable polymer and at least one core layer is bound between the layer of thermoplastic polymer and the layer of heat-sealable polymer.
7. The container seal of claim 6 wherein the at least one core layer comprises a layer of metal foil.
8. The container seal of claim 6 wherein the at least one core layer comprises a barrier film.
9. The container seal of claim 6 wherein the at least one core layer comprises a layer of paper or synthetic fabric.
10. The container seal of claim 8 wherein the barrier film is selected from the group Consisting of an oxygen barrier film, a moisture barrier film, a solvent barrier film, and a combination thereof.
11. The container seal of claim 1 wherein the liner sheet is a multilayer laminate and the second thermoplastic surface is a layer of thermoplastic polymer.
12. The container seal of claim 11 wherein the outer surface is a layer of polymeric foam or pulp board.
13. The container seal of claim 12 wherein the at least one core layer comprises a layer of metal foil.
14. The container seal of claim 12 wherein the at least one core layer comprises a barrier film.
15. The container seal of claim 12 wherein the at least one core layer comprises a layer of paper or synthetic fabric.
16. The container seal of claim 14 wherein the barrier film is selected from the group consisting of an oxygen barrier film, a moisture barrier film, a solvent barrier film, and a combination thereof.
17. The container seal of claim 11 wherein the liner sheet further comprises at least one core layer bound between the layer of compressible polymeric foam or pulp board and the layer thermoplastic polymer.
18. A two-piece container seal suitable for sealing a container having a removable closure and for lining the closure, the container seal comprising:
a flexible, multilayer laminated sealant sheet having a sealing layer at one surface and a first thermoplastic layer at the other surface thereof; and
a flexible multilayer liner sheet of the same size and shape as the sealant sheet and comprising an outer layer and a second thermoplastic layer;
the first and second thermoplastic layers being in opposed, congruent contact with each other, the first thermoplastic layer being ultrasonically welded to the second thermoplastic layer by an array of spaced, frangible ultrasonic welds, the interface between the first and second thermoplastic layers being adhesive-free.
19. The container seal of claim 18 further comprising at least one core layer between the sealing layer and the first thermoplastic Layer of the sealant sheet.
20. The container seal of claim 18 further comprising at least one core layer between the outer layer and the second thermoplastic layer of the liner sheet.
21. The container seal of claim 18 wherein at least one of the sealant sheet and the liner sheet comprises a layer of metal foil.
22. The container seal of claim 18 wherein the entire container seal is adhesive-free.
23. The container seal of claim 18 wherein the sealant sheet includes a metal foil layer bound between the sealing layer and the first thermoplastic layer.
24. The container seal of claim 23 wherein the sealing layer is a layer of heat-sealable polymer coated on a surface of the metal foil layer.