The weight of PET bottles has reduced in the past decades, thanks to developments in technology. However, barrier technologies could lead to some degradation of beverages – which is why inspection of all components is so important to ensure food safety requirements are still met, says Sidel.
Barrier technologies include additives or blends in the basic composition of PET material, or coatings on the plastic.
PET bottles can be used with beverages such as beer, juice and milk products. However, how the beverage interacts with packaging must be considered.
The benefits of light-weighting for manufacturers and beverage brands include using less plastic, reducing bottle weight and saving energy during production. Progress in light-weighting is thanks to technology developments in PET resin, PET preforms, bottle design and production equipment.
“The current drive towards ever more light-weighting of bottles does not have an effect on the properties of PET regarding food safety,” said Nicholas Bloch, executive vice president, group communications at Sidel.
“Although the thinner bottle walls do have a decreasing effect on the performance of the PET barrier, they require accurate testing of material permeability to ensure the required shelf life of the beverage is achieved - and to ensure migration of external components into the product does not take place and cause contamination.”
“All manufacturers need to be aware of other potential risks such as the migration of inks required for bottle marking or glues from the bottle labelling process through the thinner PET walls.
“PET is a biologically inert plastic, for which the materials are well-defined, needing no additives for enhanced performance and for which the manufacturing process is equally standardised. The PET bottle blow moulding process has no effect on the features of the packaging material. The actual blow moulding process stretches the material, changing its state from amorphous PET to semi-crystalline. The finished bottle has superior strength and greater barrier properties as a result.”
What does the consumer think about light-weighting?
Sidel produces a ‘RightWeight’ bottle for still water. This weighs 7.96 grams, which the company says is 34% less than the average bottle and results in cost savings of up to €1.75m ($1.95m) a year.
But what about the consumer experience of a light-weighted bottle?
“The increased resistance of the RightWeight concept bottle helps eliminate the 'over squeeze' issue often experienced by consumers when using ultra-light bottles, which can result in the spilling of contents unintentionally,” said Vincent le Guen, vice president, Sidel.
“Increased resistance also makes it easier for consumers to unscrew the cap and open the bottle. In addition, the stronger resistance means the RightWeight bottle is more likely to travel across the supply chain and retain its original attractive appearance when it is placed on a supermarket shelf in front of the consumer.”