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US 5,702,786 AGranted
Process for preparing thermoplastic polyolefin resin articles of reduced hydrocarbon permeability
AssigneeGreif Bros. Corporation
InventorRonald T. Robichaud
Life of this patent
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Abstract
A process is described for improving the hydrocarbon solvent impermeability of polyethylene resin based containers. The process employs a thermal profile during thermal molding, which creates a crystalline barrier adjacent one surface of the container. The barrier enhances impermeability of the container.
Claims9
A process for preparing polyethylene resin containing articles of reduced hydrocarbon permeability, which comprises;
- providing a thermoplastic resin composition, which comprises;
- a major proportion of a polyethylene resin;
- a minor proportion of polyvinylidene fluoride:
- and
- a binding proportion of aluminum stearate;
- feeding the resin composition to a heating zone, said zone being maintained at a temperature above the first order phase transition temperature of the polyethylene, whereby said fed composition is thermally plasticized;
- continuously passing the plasticized composition to a shaping zone wherein said plasticized composition is shaped in the form of an article having first and second surfaces;
- cooling the article first surface to a temperature between the first and the second order phase transition temperatures of the polyethylene, while maintaining the second surface at a temperature above the first order phase transition temperature for a period of time sufficient to form sperulites of crystals adjacent the first surface and then
- cooling the whole of the article to room temperture.
6 more elements
Dependencies are inferred from the claim text.