Method of making a compostable polymeric composite sheet
AssigneeClopay Plastic Products Company, Inc.
InventorsPai-Chuan Wu, Thomas R. Ryle, Leopoldo V. Cancio
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Abstract
Compostable polymeric sheets of biodegradable or environmentally degradable polymers are included. These composite sheets may be made by extrusion and are compostable in municipal solid waste treatment facilities. The composite film is formed by coextrusion of top and bottom water insoluble thermoplastic films having a water soluble polymer therebetween and stretching the composite along line space substantially uniformally across and through the depth of the composite for weakening the strength of the composite while maintaining its water impermeability.
Claims8
A method of making a compostable polymeric composite sheet comprising
- coextruding a water insoluble and impermeable top film of thermoplastic polymer and a film of water soluble polymer,
- combining a water insoluble bottom layer of thermoplastic polymer on the coextrusion side adjacent said water soluble film to form a composite with said top film and said bottom layer having said water soluble polymer therebetween, and
- stretching said composite along lines spaced substantially uniformly across the surfaces thereof and through the depth of the composite, said stretched areas being separated by unstretched areas and having a thickness less than the unstretched areas, said stretched areas for weakening the strength of said composite while maintaining its water impermeability.
Dependencies are inferred from the claim text.