Crystallizable PET shrink sleeve labels for PET bottles

In the global market of product decoration and brand promotion, shrink sleeves are poised for significant growth rates, as they provide full 360°, top-to-bottom decoration for a broad variety of packaging types such as bottles, cups, trays, etc.

Consequently, shrink sleeves may help to reduce the need for mass-colored bottles. This helps to improve the quality of recycled bottle materials and supports a wider range of applications for the recyclate.

Shrink sleeves offer an effective labeling technology that combines high quality graphics with complex container geometries to maximize shelf appeal of FMCG (Fast Moving Consumer Goods) products.

In terms of volume PETG (glycol modified PET) film is currently the most abundant film type used for shrink sleeve labels in Europe and North America and has largely replaced PVC and Polystyrene based shrink sleeves.

Historically, when recycling PET containers labeled with full body shrink sleeves, it was crucial to completely remove the shrink sleeve material from the PET bottle recycling stream to avoid subsequent processing issues with the recycled PET due to material incompatibility.

While brand owners strive to see a 100% recyclability of their packaging material, current PETG shrink sleeves are considered a disruptor for the PET bottle recycling and have to be separated from the bottle PET stream. Given the trend of thin-walled PET bottles, this situation becomes even more problematic, as a quantitative mechanical separation of shrink sleeves also leads to increased losses of PET bottle recyclate in the separation process.

In order to avoid the need for material separation and thus improve the yield and quality of rPET, crystallizable PET (cPET) has been developed as a technically comparable alternative to PETG. In contrast to PETG, crystallizable PET is compatible with the PET bottle recycling stream and does not adversely impact the rPET-quality, enabling the recycling of both materials, the bottle PET and the cPET shrink sleeve simultaneously.

However, because the shrink sleeve is printed, it is necessary to remove the printing inks during the PET bottle recycling process to avoid problems like discoloration and chemical contamination of the recycled PET. In order to ensure complete ink removal from the shrink sleeve in the existing hot washing process, Siegwerk developed washable ink solutions for all relevant printing processes for shrink sleeves. These UV-curing and solvent-based inks and primers ensure a smooth deinking of cPET-based shrink sleeves during the usual washing conditions in the PET bottle recycling process and at the same time are non-bleeding to avoid any contamination of the washing water which might affect the rPET quality.

In order to test the technical feasibility of the concept, cPET in combination with washable inks, Siegwerk partnered with Klöckner Pentaplast and MCC to unlock the use of crystallizable PET shrink sleeves in Europe in the recycling of beverage PET bottles.