Downgauging as a solution for a circular economy
Ultra-thin stretch film from PIR and PCR
Downgauging and recycling play a key role when it comes to making stretch wrap film environmentally friendly. SML’s SmartCast Infinity line is now ready for ultra-thin stretch film of only 10µm with up to 80 % post-industrial recyclate (PIR). For manufacturing pre-stretch film with a thickness of 8µm, SML has developed a specific recipe for post-consumer recyclate (PCR).
The new formulations for the manufacturing of ultra-thin stretch wrap films from PIR and PCR are the fruit of intensive R&D work: in 2020, SML succeeded in producing film with an ultimate elongation value of 400 % by using up to 80 % PIR. “We started our trials with a film thickness of 23µm. Following the first positive analyses, we began to reduce the thickness step by step,” Thomas Rauscher, Product Manager for Cast Stretch Film, explains. Finally, 10µm film with a high content of PIR could also be realised and qualified. “Looking at these results, downgauging with PIR is also a solution. The film’s quality is totally in line with market requirements and the optical properties are excellent," Thomas Rauscher adds.
Field tested: stretch film from PCR
The use of post-consumer recyclate is technically more challenging than the manufacturing of ultra-thin stretch film from PIR. With high-quality PCR, SML reaches re-feeding rates of up to 60 % on its SmartCast Infinity lines. However, in a sustainable circular economy, where cast stretch films are frequently recycled, a general recommendation is a ratio of 30 %
PCR in combination with 70 % virgin material. Beside the use of post-consumer recyclate, it is downgauging which really further increases the environmental compatibility of stretch wrap film with PCR. “In our trials on our SmartCast Infinity line, we used PCR to manufacture different stretch wrap films from 23µm down to 12µm for jumbo, machine and hand rolls. Subsequently, these products were then tested and utilised by end-users – with very positive feedback,” Thomas Rauscher comments.
PCR for Pre-Stretched Film
“Pre-stretch film” is becoming increasingly important with regard to safe film usage. The usual thickness of the final product ranges from 6 - 9µm. This makes pre-stretch film an ideal solution, e.g. for logistics and warehouses, where it can help to make processes more eco-friendly by drastically reducing film usage. Based on the model employed to manufacture “conventional” pre-stretch film, SML has developed a specific PCR-recipe for film that can be pre-stretched offline in a secondary process. The film developed by SML has 16µm and was pre-stretched down to a final 8µm. Tested at different customer sites, the film met all of the quality and usability criteria. “Generally, the processing of PIR and PCR produced very good results, both in in-house tests and also with regard to direct feedback received from consumers. This gives sound cause for optimism, that a working circular economy can be achieved in this segment in the foreseeable future”, Rauscher concludes.