Peelable laminated structures and process for production thereof
First Claim
1. A sealed container comprising a hollow body for holding an object, an opening in a wall of said body, a rim surrounding said opening and a flexible closure element overlapping and attached to said rim and closing said opening, said rim comprising a layer of a metal selected from the group consisting of aluminum and aluminum alloys that are anodizable to form a porous anodic surface film, at least one other layer selected from the group consisting of a portion of the wall of said hollow body and a portion of the closure element and a bonding structure attaching the metal at least one layer to the other layer, said bonding structure comprising a porous anodic film incorporating an internal stratum that is weakened in comparison to a remainder of the anodic film and that has a peel strength high enough to resist separation of the bonding structure at said weakened stratum except upon deliberate peeling apart of said body and said closure element at said rim, wherein said anodic film incorporating said stratum is a film produced by porous anodization of a surface of said metal layer in an electrolyte and at a voltage which results in the formation of said porous anodic film, continuing said porous anodization while carrying out a voltage reduction procedure in order to introduce a weakened stratum into said anodic film, and allowing said film to stand in said electrolyte or other acidic solution for a period of time to further weaken said film along said stratum;
- and wherein said at least one other layer is attached to said anodic film of said bonding structure by an adhesive, said adhesive having a peel strength greater than said peel strength of said weakened stratum.
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Accused Products
Abstract
The invention provides a peelable laminated structure suitable for use in a peelable seal joining a flexible closure element (23) to a container (20) or in foil/polymer laminates used for packaging and the like. The structure comprises a porous-anodizable metal substrate (11) and a porous anodic film (12) overlying and attached to a surface of the substrate. The porous anodic film (12) has a weakened stratum (19) positioned between an outer film part and an underlying structure including the metal substrate (11). The weakened stratum (19) is strong enough in use of said structure to prevent detachment of the outer film part from the underlying structure, except by deliberate peeling of the flexible closure element (23). The invention also relates to a process for producing the structure and to peelable containers and recyclable laminates incorporating the structure. The structure provides a peeable interface which is not greatly dependent on the characteristics of particular adhesives or bonding techniques used to adhere the metal substrate (11) to the remaining structure, and is thus stable and reliable.
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Citations
5 Claims
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1. A sealed container comprising a hollow body for holding an object, an opening in a wall of said body, a rim surrounding said opening and a flexible closure element overlapping and attached to said rim and closing said opening, said rim comprising a layer of a metal selected from the group consisting of aluminum and aluminum alloys that are anodizable to form a porous anodic surface film, at least one other layer selected from the group consisting of a portion of the wall of said hollow body and a portion of the closure element and a bonding structure attaching the metal at least one layer to the other layer, said bonding structure comprising a porous anodic film incorporating an internal stratum that is weakened in comparison to a remainder of the anodic film and that has a peel strength high enough to resist separation of the bonding structure at said weakened stratum except upon deliberate peeling apart of said body and said closure element at said rim, wherein said anodic film incorporating said stratum is a film produced by porous anodization of a surface of said metal layer in an electrolyte and at a voltage which results in the formation of said porous anodic film, continuing said porous anodization while carrying out a voltage reduction procedure in order to introduce a weakened stratum into said anodic film, and allowing said film to stand in said electrolyte or other acidic solution for a period of time to further weaken said film along said stratum;
- and wherein said at least one other layer is attached to said anodic film of said bonding structure by an adhesive, said adhesive having a peel strength greater than said peel strength of said weakened stratum.
- View Dependent Claims (2, 3, 5)
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4. A container comprising a hollow body for holding an object, an opening in a wall of said body, and a rim surrounding said opening suitable for attaching a flexible closure element for closing said opening, said rim incorporating a layer of a metal selected from the group consisting of aluminum and aluminum alloys that are anodizable to form a porous anodic surface film and a bonding structure for attaching the metal layer to said flexible closure element, said bonding structure comprising a porous anodic film and incorporating an internal stratum that is weakened in comparison to a remainder of the anodic film and that has a peel strength high enough, after attachment of said flexible closure element, to resist separation of the bonding structure at said weakened stratum, except upon deliberate peeling apart of said body and said closure element at said rim, wherein said anodic film incorporating said stratum is a film produced by porous anodization of a surface of said metal layer in an electrolyte and at a voltage which results in the formation of said porous anodic film, continuing said porous anodization while carrying out a voltage reduction procedure in order to introduce a weakened stratum into said anodic film, and allowing said film to stand in said electrolyte or other acidic solution for a period of time to further weaken said film along said stratum;
- and wherein a layer of adhesive overlies and is attached to said porous anodic film of said bonding structure, said adhesive having a peel strength, when attached to said closure element, greater than the peel strength of said weakened stratum.
Specification