Stora Enso Oyj

Borealis Technology Oy

Martti Vähälä

Tapani Penttinen

Kimmo Nevalainen

Markku Sainio

Jalliina Järvinen

Erkki Laiho

Hannu Salminen

Arja Lehtinen

The invention relates to a multi-layer heat-sealable packaging material especially for food packages. In addition, objects of the invention are a food package formed of the said packaging material, a method of packaging, and the use of the material for packages. The packaging material () comprises a middle layer () of fibre material, such as cardboard; at least one polymeric protective layer () protecting the product from going bad; and polymeric heat sealing layers () preferably on both sides of the packaging material. According to the invention, the heat sealing layer () forming the inner surface of the closed package, is blended with light-absorbing pigment, such as carbon black, for protecting the product from visible light. By further blending white pigment, such as titanium dioxide, into the heat sealing layer (), a grey tint resembling an aluminium foil has been achieved for the layer. The heat sealing polymer may be low-density polyethylene (PE-LD), and an oxygen and aroma proof sealing layer () of, for example, ethylene vinyl alcohol copolymer (EVOH) or polyamide (PA) may be provided between it and the cardboard ().

Aluminum-colored multilayer heat-sealable packaging material

This invention concerns a process for coating a substrate, and an extrusion coating structure. According to the present process, the coating is provided by producing a bimodal polyethylene composition by subjecting ethylene, optionally with hydrogen and/or comonomers to polymerization or copolymerization reactions in a multistage polymerization sequence of successive polymerization stages. The polymerization reactions are carried out in the presence of a single site catalyst capable of forming a composition which comprises a low molecular weight component with an MFRof 20 g/10 min or more and a density higher than the density of the composition, and a high molecular weight component, said composition having a melt flow rate MFRof 5 g/10 min or more and a density of 915&#x2013;960 kg/m. The composition is extruded on the substrate as such or by adding 10 wt-% or less, calculated from the total weight of the coating, of high pressure PE-LD by blending into the extrusion composition or by coextrusion.

Process for producing a polyethylene coating on a substrate

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Porvoo, Finland

Martti Vähälä