Polymers, Colloids and Interfaces, Invited Lecture
Retort tie-layer: the development of a solution for barrier retort structures
E. Kupsch1
1Dow Europe GmbH, Bachtobelstrasse 3, 8810 Horgen, Switzerland
The presented work aims at the development of adhesive resins for steam sterilizable film applications in food and medical packaging that promote the adhesion between polypropylene and oxygen / carbon dioxide gas barrier polymers like polyethylene vinyl alcohol (EVOH) and polyamide (PA). Generally the adhesive resin design is based on maleic anhydride grafted polymers. The different challenges between polyethylene and polypropylene grafting are discussed. To overcome these deficiencies for the adhesive resin design, a Dow developed compatibiliser for polypropylene/polyethylene blends was used in the adhesive resin formulation. The concept of the compatibilising polymer is demonstrated with an electron microscopy analysis of blends containing different ratios of polypropylene, polyethylene and compatibiliser. Finally it could be demonstrated that in multi-layer extruded film the resulting adhesive resin formulation proves to be high in adhesion strength to polypropylene, polyethylene vinyl alcohol and polyamide without performance loss after the steam sterilization process.