PRLog - Feb. 6, 2011 - DEESIDE, U.K. -- A consortium project team consisting of Systems Labelling, a leading bottle manufacturer and a leading UK dairy brand have completed an 18 month project resulting in a groundbreaking development for the dairy industry. The WRAP funded project set out to identify the root cause of colour contamination in rHDPE pellets in order to increase the proportion of recycled material used when producing HDPE liquid milk bottles. The combined solution encompassing packaging design, methods, materials and recycling processes has delivered a potential increase from 10% up to 50% rHDPE content in blown liquid milk bottles. Given the Milk Roadmap Target to reach 50% rHDPE was set for 2020 this is a positive step forward. The consortium engaged the leading HDPE reprocessing plants in the UK, recycling equipment manufacturers and chemical suppliers in Europe and associated specialists to conduct a series of laboratory and medium scale trials to develop workable solutions through a process of elimination.
Polypropylene Adhesive & Paper Adhesive Labels
Labelling was a key work-stream within the project with some significant findings. Initial mini wash trials discovered that paper labels break up and the laminate and ink removed in the hot wash in turn cross-contaminating the clean HDPE flakes. The recycling operations also found that the build up of paper pulp in their equipment is an issue causing equipment breakages and down time. However PP labels were found to remain intact and peeled away from the HDPE flakes. The encapsulated labels did not release ink into the wash water and the specialist detergent was found to nullify the tack of the adhesive which was removed and formed a residue in the wash water. Medium scale trials demonstrated that the released PP labels are removed from the HDPE flake via the air separation equipment resulting in a label removal of (>99%).
The consortium found the wash conditions are key to the successful removal of labels and the trials found that 85 degrees centigrade for 10 minutes with a 2% detergent dosing performed best in terms of label removal and cleanliness of flake. The importance of using a suitable adhesive product fit for purpose in a cold and wet environment is vital. A detailed specification is included in the full report available at http://www.wrap.org.uk/
However from a commercial perspective Systems Labelling can offer a "no on cost solution" when switching from paper to synthetic labels.
In short the project consortium identified that synthetic (polyproplylene)
During recycling trials the optimum conditions resulted in twice as many PP labels removed compared to the paper labels tested. The labels still attached to washed HDPE flakes can be missed by colour sorting equipment as the laminate and ink is broken down and removed from paper labels in the hot wash cycle. This in turn contaminates the water and cross contaminates clean HDPE flakes.
Given that adhesive labels make up approximately 70% of the market the development of a fully removable PP label is clearly significant. It is also of note that the pulp and paper label waste builds up as sediment and when collected sent to landfill whereas synthetic labels can be collected in a float tank and air separators for recycling into various polyolefin compounds.
The pictures below compare the laboratory washed PP labels (which peeled away from the flake forming cigar shapes) to the washed paper adhesive labels (of which a high proportion remain intact and/or breakdown losing ink and overlaminate film.)
The full WRAP Report MDP025 entitled “Research & Development to improve the recyclability of plastic milk bottles.” can be viewed or downloaded at wrap.org.uk/
Alternatively visit http://www.systemslabelling.com for a link or to post a question to our team of experts. Such as; how much can other sectors and products benefit from these conclusions?
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Systems Labelling are a world class producer of labels. They are located in the UK and their products feature across a wide range of consumable industries such as dairy, food, chemical, household, and cosmetics. Customers include RBS, M&S, Asda and Tesco.