| Abstract |
The proposal aims to explore the potential for manufacturing containers (e.g. food, aerosols and beverage) from polymer-coated steel sheet. The requirement to innovate in terms of forming cans from new composite materials responds to increasing consumer demands for attractive and differentiated packaging in these sectors, and to the concurrent move towards brand reinforcement via packaging that is a key goal for retailers and fillers. In addition, the utilisation of polymer coated steel sheet can help address the underlying pressure on can producers and raw material suppliers to reduce costs, lightweight products and be more eco-friendly. To this end, the project seeks to develop polymer coated sheet systems and design new container configurations, together with appropriate industrially applicable forming processes, to allow steel based containers to compete more effectively with alternative systems.
Significant progress has taken place over the last few years with cans in terms of ligthweighting, product differentiation by shaping and recycling. However, it is clear that to remain competitive with other packaging alternatives, further major technological advancements will be essential during the next decade which are anticipated to be based on the use of polymer coated steel sheet.
Food, aerosol and beverage cans are formed using a variety of processes including stretch draw, deep draw and the Draw and Wall Ironing (DWI). DWI is one of the most common production method for the manufacture of cans in which a thin metal blank is subjected to a deep drawing step, followed by a wall ironing operation, resulting in a thin walled cylindrical end product. After the DWI stage, the cans are subjected to a washing and coating process that removes lubricants and applies a base coating to the metal. Then, the inside of the can is subjected to one or more lacquer operations to prevent contamination of the contents by the steel. An external coating is also applied not only to protect the container against corrosion, but also has a decorative function. Currently all can processes utilise these conventional, lacquered, materials which have deficiencies with respect to the economics of production, the functionality of the coating, as well as environmental and food legislation issues.
Polymer coated materials give the opportunity to implement new, improved technological features (such as formability, high barrier levels, printability etc) that overcome these drawbacks. A typical multi-layered polymer coated sheet is illustrated in Figure 1, where it is seen that three layers are deposited onto the steel (ECCS) faces, each of which has a specific role. |
