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US 5,628,832 AGranted
Removal of adhesive from polyester film
AssigneeE. I. Du Pont de Nemours and Company
InventorsWilliam E. Graham, Richard R. M. Jones
Life of this patent
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Abstract
Adhesive is removed from polyester film which is initially formed into a flake followed by a series of removal and separating steps. In a preferred mode a clarified liquid which results from stripping solution is recycled for further use in adhesive removal.
Claims3
A process for removal of an adhesive coating layer from polyester film comprising the steps of:
- (a) forming a section of film into a series of flakes,
- (b) contacting the flakes with an aqueous alkaline stripping solution comprising a surfactant selected from the group consisting of (i) an anionic surfactant and a nonionic surfactant and (ii) a surfactant having both anionic and nonionic functionality whereby the adhesive coating is removed from the polyester,
- (c) separating undissolved solids from step (b) to recover separately polyester flake and a slurry comprising stripping solution, surfactant and a solid residue resulting from the adhesive coating layer,
- (d) rinsing the polyester flake with a rinse stream,
- (e) separating the slurry into a clarified liquid and a concentrate,
- (f) repeating step (a) through step (d) on additional flake with at least a portion of the clarified liquid from step (e) recycled into step (b).
3 more elements
Dependencies are inferred from the claim text.