Stora Enso Oyj

Mohammad Khajeheian

Jari Räsänen

Kimmo Nevalainen

Ville Ribu

Ari Rosling

Jurkka Kuusipalo

Outi Kylliäinen

Sami Kotkamo

Mikko Tuominen

Ella Lindström

Mikko Touminen

The invention relates to methods for lowering the melt viscosity and thereby improving heat-sealability of a polyester. The invention also relates to a method for manufacturing a heat-sealed container or package from fibrous-based, polyester-coated packaging material, and a method for heat-sealing polyester. The solution according to the invention is subjecting polyester to electron beam (EB) radiation. The lowered melt viscosity allows a lower heat-sealing temperature, and permits sealing of polyester to an uncoated fibrous surface. The preferred polyester for the invention is polylactide, as such or as blended with another polyester.

Methods for lowering melt viscosity and improving heat-sealability of polyester and for manufacturing a heat-sealed container or package

The invention relates to use of polylactide (PLA) as an extruded polymer coating on paper or board intended for the production of containers and packages, which are heated in a stove or microwave oven. According to the invention a polyfunctional cross-linking agent, such as trialkyl isocyanurate (TAIC), is blended with PLA, and the extruded coating layer is subjected to cross-linking electron beam (EB) radiation. PLA may be used as such or blended with another biodegradable polyester such as polybutylene succinate (PBS). EB radiation has been found to improve adhesion of the coating to the paper or board substrate, heat-scalability of the coating, and heat-resistance of the finished containers and packages.

Method of use of polylactide and manufacturing a heat-sealed paper or board container or package

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Turku, Finland

Mohammad Khajeheian