A successful trial of de-inking LDPE packaging films for recycling has been achieved by German firms Siegwerk and APK AG.
The two companies have collaborated since October 2019 on developing the trial on de-inking process of twofold printed LDPE-films.
APK AG is a specialist in the production of high-quality plastic recyclate from packaging waste, while Siegwerk is a provider of printing inks for packaging applications and labels.
Siegwerk head of circular economy hub Alina Marm said: “Design for recycling – ideally enabling product to product recycling – is crucial to closing the loop for flexible packaging.
“For Siegwerk this means providing innovative printing inks and lacquers, which facilitate high-quality recycling, for example by allowing de-inking while keeping full performance during the use phase.”
Printing inks are vital for the functionality and appearance of packaging, but represent a major challenge when it comes to manufacturing a plastic recyclate of sound quality from post-consumer packaging waste.
APK AG chief executive Klaus Wohnig added: “The goal of a quality-driven recycling process is to create a recyclate, which is as transparent as feasible and which can once more be reused in packaging applications. Successful de-inking is essential.”
In the trials, the Research and Development unit of APK AG tested a number of LDPE film samples that had been printed twofold with yellow, red, black and blue inks from Siegwerk.
The test series aimed to establish whether APK AG’s solvent-based recycling technology Newcycling could fully remove these inks from the polymer matrix.
These film samples were treated with the Newcycling solvent and dissolved. The obtained polymer solution still contained printing ink-components though.
The dispersed inks were then removed with a filter unit explicitly designed for the process of de-inking, featuring a very high sensitivity level.
Tests of the red, black and blue samples produced a near virgin transparency. In the case of the film printed with yellow ink, a marginal colouring remained.
