Tinted coloured caps and synthetic self adhesive labels instead of fully dyed caps and paper labels may be implemented across the milk bottle production line in order to increase recycled content.
Following research by WRAP a report called, Research & development to improve the recyclability of plastic milk bottles, has been produced. This study shows that by reducing the amount of pigment in milk bottle caps, material contamination when recycling the bottle is minimal. Therefore, this would enable bottles with more than 30% rHDPE to be acceptable from a colour perspective.
Currently, if caps mistakenly enter the milk bottle recycling stream, the cap colour - which signifies to the consumer the type of milk, - can cause a hue to the rHDPE pellet, therefore contaminating it. Certain types of labels were also thought to contribute to the hue problem.
WRAP found that ink from paper labels contaminated the water and cross-contaminated HDPE flakes. One reprocessor also noted that the build up of paper pulp causes damage to reprocessing equipment. It was concluded that switching from paper to PP self-adhesive labels would improve the hue of material, although companies would incur a 3-5% increase in label material costs.
The report said: “The next steps for the industry would be to carry out large-scale trial of these quick wins prior to implementation.”
The Milk Roadmap has set the diary industry targets to achieve 30% recycled content by 2015 or sooner and 50% recycled content by 2020.