Research evaluates the impact of printing inks on recyclability of plastic films
The PrintCYC consortium was established in 2019 to support the transformation of printed polyolefine-based packaging films towards a circular economy by evidence-based industrial trials. The initiative is coordinated by Dr Annett Kaeding-Koppers, an independent packaging expert and sustainability consultant. PrintCYC is connected to converters and in continuous dialogue with brandowners, recyclers, and platforms such as Ceflex and Forum Rezyklat to discuss and share results.
Key stakeholders are leading machine manufacturers such as Brückner Maschinenbau, Erema, the Brückner Group members Kiefel and PackSYS Global, the printing ink manufacturer hubergroup Print Solutions, and Profol, one of the market leaders for PP cast films. In the technology center of Brückner Maschinenbau, the regranulates produced from printed films were used for the production of sequentially as well as simultaneously stretched films. The final analysis of the samples in the film laboratory showed that the film properties were quite convincing even with a 100% regranulate content. The regranulates were also successfully used in the production of cups, trays and tubes.
The influence of pigments on recyclability
At the beginning of this year, PrintCYC started into the next project phase, investigating the impact of pigments on the recyclability of printed packaging films. Inorganic pigments are mostly temperature stable and therefore supposed to be recyclable without degradation. However, organic azo-pigments like most standard red and yellow pigments are more temperature sensitive and might re-split into critical components.
Both pigment types showed excellent recyclability, leading to odour- and defect-free, colour-stable PP recyclates. The material properties of the coloured recyclates were analysed technically and analytically. After the first recycling loop, PrintCYC found no significant impact on material properties compared to virgin reference. Based on a specific migration screening test, the renowned Swiss quality testing laboratory SQTS evaluated the PP recyclates. The positive results open a wide range of reuse in different film and packaging applications.
For the next project phases, PrintCYC is looking for partners to test and evaluate closed loop printed PP packaging scenarios and to further improve relevant design for recycling guidelines.
