New PET yogurt pots and probiotic bottles
PET is the recyclable material par excellence, especially when it comes to ‘food grade’ re-use. That's why the SACMI Rigid Packaging Laboratory has developed a project to extend its application range so it can replace, to name just a few, traditional polystyrene (PS), high-density polyethylene (HDPE) or the polypropylene (PP) used to make the classic yogurt pots and probiotic drink bottles.
Already prototyped by the Lab and tested in the field by key customers, the new products - yoghurt pots and probiotic bottles - make the very most of SACMI's know-how and expertise in compression and stretch-blowing. The process is a two-stage one, similar, as far as blow-molding is concerned, to that used to make beverage containers, but with a key difference: to produce the preforms, SACMI uses compression, a process in which it is the world leader.
Thanks to the innate advantages of compression - lower material extrusion temperature, no gate or hot runners in the mold - it is, in fact, possible to develop lighter, higher-performance containers with shorter cycle times, making the solution potentially advantageous and easy to apply.
This difference paves the way for bottle-to-bottle solutions (i.e. the ability to connect container disposal directly with subsequent melting of the resin, which can then be fed directly back to preform production and the subsequent container stretch-blow molding stage.
This yields unmatched versatility: simply changing the forming mold used during blow-molding generates infinite design opportunities, allowing for easier segmentation by brand/product and the development of unique, distinctive shapes. Both containers and bottles can be made of transparent PET or, if necessary, colored or sleeved PET.
Currently limited to dairy, the proposed application has potential in other industries (cosmetics, pharma) and, with other food-contact products (such as spice jars). Needless to day, the SACMI Laboratory is constantly researching and validating new products. The PET outlook appears even brighter when one considers that governments may, in the future, impose higher taxes on resins/plastics that not do not come from recycling (not to mention the fact that the cost of the resin now accounts for at least 80% of container cost).
The plastic-free revolution: cellulose
Cellulose is nature’s most abundant biopolymer, and is fully recyclable within the classic paper recycling chain. Hence the keen interest in a second line of research, in which the SACMI Laboratory has reached the first milestone on a journey towards a plastic-free rigid packaging future.
The result is a cap made entirely of cellulose fiber, produced by way of an innovative dry molding process. This ambitious challenge involved testing a broad range of materials (powdered cellulose, cloths, wadding, etc.) with widely differing qualities/characteristics and validating their applicability-adaptability to the product.
One of the avenues explored was that of feeding the system with high-purity cellulose; this is subsequently ‘pulped’ and transformed into a moldable material, with additives being used to give the material the necessary resistance to water absorption. It is then ‘pressed’ inside an innovative mold which, compared to a traditional wet molding process, has the further advantage of not consuming water and allowing very short cycle times.
Using special lab machines, SACMI has already developed and tested new capsules and caps made entirely of cellulose fiber. Moreover, in this field SACMI also works with leading Italian and international universities and major food product packaging companies. A development that could, once again, open up new horizons, such as on-site waste recycling, as part of a drive towards ‘complete process circularity’.
Research is currently focusing on capsules and caps but in future the SACMI laboratory will extend its efforts to containers, such as those used for coffee.
The ‘composites’ opportunity
‘Complete’ recycling for food-grade use - or, indeed, the prospect of completely plastic-free rigid packaging - is not the only area being explored by the SACMI Rigid Packaging Laboratory. Further opportunities await: these include the development of ‘composite’ materials that remain suitably compostable yet, at the same time, offer better functional characteristics on the basis of the specific product-process.
For example, a further research project focuses on PHAs (polyhydroxyalkanoates) and materials that can, in any case, be composted at home. As with PET, the tested process is similar to compression molding, and offers all the relative advantages plus the ability to use a higher fiber content in the material.