Paneling occurs when the pressure inside a plastic bottle becomes less than the air pressure outside of the bottle. When this happens the walls of the plastic bottle begin to collapse inward. This not only affects the bottle, but the label has a tendency to peel off as well. So how do we stop this from happening? Paneling can be stopped through the fluorination of plastic bottles.
What is Fluorination?
Fluorination process creates a barrier between the liquid contents and the walls of a plastic bottle, reducing the likelihood that the bottle shape will either collapse and sink inward or puff outward during a products shelf life expectancy. Benefits of fluorination are; minimizing product evaporation, reducing chemical permeation through the walls of the bottle, which in turn reduces odor emission, and protects against flavor or fragrance loss. Fluorination is a process that minimizes the distortion of the container, referred to as paneling, by treating both the inside and outside surfaces of the plastic bottle with fluorine gas. The gas creates a permanent barrier on the exposed surfaces. The fluorination process can be performed either during the manufacturing process or after the bottle is manufactured as a secondary operation.
Post mold fluorination: plastic bottles that are already formed are exposed to fluorine gas in a sealed reactor, binding with the plastic replacing/exchanging a percentage of hydrogen atoms with fluorine atoms, making the polyethylene or polypropylene plastic bottle more resistant to product attack and minimizing product evaporation. In-mold fluorination occurs when fluorine and nitrogen are added to the blow molding process at the point of production. Through this process, different levels of fluorination can be used, depending on the product that is being stored in the container.
Once satisfactory barrier performance has been demonstrated through shelf life testing, it is important to note that small and subtle changes in either a product formulation and or a change in a bottle pigment ( natural to white) can influence the fluorination chemistry. Care must be taken not to change the liquid formula being contained or the bottle pigment without requalification/testing.
Fluorination is available for use on all polyethylene and polypropylene containers. Common products that can cause paneling, and may require fluorination are cleaners and solvents, essential oils, car products, paint thinners, and shampoos.