Polymer coated steel in Europe With regard to the packaging industry, one of steel's priorities over the years has been to improve continuously its products in order to meet the increasingly stringent demands put on today's packaging materials. Among these, an excellent barrier to moisture and resistance to aggressive products are particularly essential requirements. The industry has responded to these specific demands by developing the polymer coated steel process. Indeed the steel substrates (whether tinplate or electrolytic chromium coated steel) laminated with thermo-plastic polymer films (either polyethylene terephthalate/PET or polypropylene /PP) combine the recognised advantages of steel with those of modern coating technology. An excellent appearance, abrasion resistance and high moisture barrier, even after forming, are some of the benefits of polymer coated steel.   Polymer coated steel, a packaging material which combines the recognised advantages of steel with those of modern coating technology.   3 production processes   Ferrolite produced by Corus Packaging Plus. under licence from CarnaudMetalbox : The substrate is pre-heated prior to entering the film application stage where PET is applied on the external surface of the steel (advantages : high resistance to abrasion and glossy appearance), and PP on the internal surface (advantage : excellent protective barrier against contents). Different film types and colours of varying thicknesses can be applied simultaneously to opposing surfaces. Once the films have been applied, the resultant composite strip then passes through a second induction heater which completely melts the polymer films. The strip is maintained at a temperature in excess of 260°C for a few seconds before quenching under carefully controlled conditions in a water bath.     Andrafol produced by Rasselstein Hoesch/Germany under licence from Toyo Kohan. The manufacturing process of Andrafol allows simultaneous coating of both surfaces with different coating materials of various thicknesses. It is possible either to coat one side with PP-film or to laminate the strip on one or both sides with PET-film or lacquer. The combination of film/lacquer is also possible. For these applications, 4 different coating methods are used : Method A : without any adhesive agent a PET-film is thermally laminated on to ECCS in a continuous process, free of solvent. Method C : an adhesive is applied to tinplate or ECCS prior to laminating a PET or PP-film onto the wide coil. Method B : a PET-film, which has previously been provided with an adhesive layer, is applied to ECCS in a continuous process, free of solvent. Final adhesion of this coating is achieved by the drying process after lacquering/printing of the plain side.   Method D : wide coils of tinplate or ECCS are coated with lacquer by roller application. The lacquer is dried and then cured in a drying oven. HandySkin produced by Cockerill Sambre/Belgium : a transparent or coloured varnish laid in between the steel substrates and the polymer film helps the film adhesion on steel, while offering flexibility in the range of colours available for brand differentiation. Moreover, it is also possible to lacquer the surface which has not been laminated with polymer films.   Polymer coated steel applications Today, polymer coated steel is a recognised packaging material in the production of steel aerosol components, such as tops, bottoms and valve cups. It is especially suited to aerosol cans stored in humid conditions, such as bathrooms and kitchens, owing to the excellent abrasion and corrosion resistance provided by the product. It is also suitable for particularly aggressive products, owing to the first class barrier properties of the films. Moreover, by using polymer coated steel with a thick internal coating of polypropylene for valve cups, a good seal between the internal surface of the cup and the aerosol top is formed, eliminating the need for the fitting of rubber gaskets. Finally, it looks good, particularly with the various colours available, which can be matched with brand designs. Development in this segment is being carried out today on a polymer coated steel aerosol can body. The advantage of this would be a further improved water tightness of the steel can, specifically for highly aggressive products which are a challenge to pack.   Polymer coated steel used for tops, bottoms and valve cups of steel cans in addition to easy open ends for food products   Other applications Due to its outstanding performance, polymer coated steel lends itself to other packaging applications in the food and beverage seg-ments, as well as for general line components and speciality packaging. Used for easy open ends on baby food, quality cooking sauces and milk pudding cans, polymer coated steel has a clean appearance, whilst providing reliable anticorrosive properties in the rivet, score line area and inside the lid. It can also be used for the ring component of easy peel ends, which has particular benefits for children and the elderly, being safe and easy to open. Generally speaking, polymer coated steel is well suited for food container applications. It offers excellent protection for retorted food, in no way affecting the food's natural flavour, and the clean white colour contrasts well with the content, enhancing its appearance. In food tray applications for instance, polymer coated steel remains rigid when hot, and can be readily sealed with various lidding systems. Moreover, the major advantage of these polymer coated steel trays is that they are microwavable, cooking food evenly, while remaining rigid when taken out of the oven. Moreover, they are strong, which is particularly important during the filling stage, but also for transportation and handling by both retailers and end-consumers. Polymer coated steel technology is widespread in Japan in the beverage segment, where TULC (Toyo Ultimate Lightweight Can) is enjoying considerable growth. In 1997 Corus Packaging Plus, inconjunction with the Redicon Corporation, launched a new technology called RBS, where the heat sealed bond of the polymer offers excellent opportunities for formability. Moreover, this ensures excellent barrier properties and a higher resistance to external damage. Polymer coated steel used for general line components such as plug lids and paint can rings, assures outstanding corrosion resistance and improved sealing functions. This is particularly appropriate for water based products, and has been adapted to satisfy the current developments in the paint industry for water based formulations. Other applications in this general line segment include the seal on drums when used for hazardous chemicals.   Polymer coated steel is well suited for food container applications such as food trays, for example   Polymer coated steel and the environment The recyclability of the polymer coated steel argues for the increasing use of this packaging material. Indeed, the polymer films do not disrupt the recycling process of steel. Conclusion The versatility of polymer coated steel enables new solutions and applications to be developed, as this material facilitates improvements in packaging performance, from the viewpoint of longevity of storage, market appeal and ease of use for the consumer.