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Primary recycling of polyolefin-mixed films for high-added value applications in the blow moulding industry

Final Report Summary - RECFINMIX (Primary recycling of polyolefin-mixed films for high-added value applications in the blow moulding industry)

At the moment about 1.5 million tonnes of plastic are being recycled yearly, 75 % of which is polyethylene, both low density (LDPE) and high density (HDPE). Recycling of plastic film is by far one of the weakest points in all recycling schemes. The reason for this failure is that post-consumer plastic film waste is usually a mixture of diverse plastics, especially LDPE, HDPE and polypropylene (PP), which together comprises 95 % of the total film. Although cleaning and separation of the polyolefins (LDPE, HDPE and PP) from the rest is easy using flotation or hydrocycloning methods, separation of LDPE, HDPE and PP from each other is difficult, since their respective densities are very similar, and their variable shape do not allow the use of automated, sensor-based methods (such as use of near-infrared detection).

The overall objectives of the RECFINMIX project were both ambitious and strategic for the SME partners involved in view of the current and foreseeable market trends. The consortium comprised six small to medium-sized enterprises (SMEs) and three research organisations from five different EU countries, and covered all the steps regarding separation and recycling to obtain LDPE suitable for production of blown film from waste polyolefin film mixtures and the development of equipment for such a purpose.

A method to separate mixed polyolefin film waste has been developed. Two streams of polyolefin have been obtained, a high added-value LDPE stream suitable for production of blown film and with less than 5% HDPE and PP impurities, and a low value HDPE-PP stream with less than 20 % LDPE impurities. This is only suitable for injection moulding. A semi-industrial pilot separator for mixed polyolefin film waste has been constructed.

During the project, technical deviations were found and they were successfully solved. For instance, it was shown that the temperature distribution along the drum was heterogeneous, since only the first part of the cylinder was heated at the programmed temperature. After a deep study, the problem was located and solved. Therefore, modifications were made on the semi-industrial cylinder.

The project RECFINMIX intends to develop a method to separate from mixed polyolefin film wastes a stream of LDPE with less than 5 % impurities, and therefore suitable for film blowing.