Stora Enso Oyj

Tapio Koskinen

Tapani Penttinen

Kimmo Nevalainen

Jurkka Kuusipalo

Sami Kotkamo

A method for improving the heat sealability of a packaging material and a method for manufacturing a heat-sealed container or package are described. The material can be polymer-coated packaging paper or cardboard, or a polymeric packaging film. The material includes a polymer layer that contains polyester, particularly polylactide, the heat sealability of which is improved by ultraviolet radiation. Polylactide is useful as such or when blended, for example, with other biodegradable polyester. The containers and packages thus manufactured include disposable drinking cups and cardboard carton and box packages.

Method for improving the heat sealability of packaging material and method for manufacturing heat-sealed container or package

A heat-sealable biodegradable packaging material, its manufacturing method and a product package formed thereof, where the packaging material comprises a fiber substrate, an inner polymeric coating layer against the fiber substrate, which contains polylactide and a biodegradable polyester that is blended therewith to improve the adhesion between the inner coating layer and the fiber substrate, and an outer coating layer that constitutes the outer surface of the material and contains polylactide and a biodegradable polyester that is blended therewith to improve the heat sealing ability of the layer, the portion of polylactide in the inner layer present in an amount greater than that in the outer layer. The inner and/or outer coating layers can further have blended therewith a small amount of acrylic copolymer that improves the adhesion and/or heat sealing ability. The coating layers can be introduced onto the fiber substrate by extrusion or coextrusion.

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Tampere, Finland

Tapio Koskinen