Kirin enhances consumer safety in PET bottles with thin film deposition tech
24 Feb 2021 --- Kirin Holdings has developed a new thin film deposition technology for PET bottles using a hot wire technique.
Developed at the Japanese company’s Packaging Innovation Laboratory, the new technology addresses potential oxidation concerns arising from the thinning and lightweighting of PET bottles targeting plastic reductions.
The hot wire technique contributes to resource conservation by forming a colorless, transparent and recyclable gas barrier film on PET bottles, preventing content degradation while reducing bottle weight.
“Coating the inner surface of PET bottles with a thin gas barrier film prevents oxygen from flowing into the bottle, carbon dioxide from flowing out, and water vapor from flowing out through the bottle wall,” Satoru Kinoshita from Research Laboratories for Packaging Innovation of Kirin Holdings, tells PackagingInsights.
The hot wire technique forms a colorless, transparent film on PET bottles. The technology targets beverages susceptible to oxidative deterioration, such as beer, wine, green tea and carbonated beverages. It also applies to containers with extremely thin bottle walls where water vapor can easily escape.
Food safety first
Kirin’s new chemical vapor deposition (CVD) system first fills PET bottles with gas. Then, a ceramic rod raises the internal temperature to deposit decomposed gas on the PET bottle’s inner surface. The decomposed gas forms a film that prevents permeation.
The technology ensures no risks to food safety after the PET bottles undergo the CVD treatment.
“[The technology] is registered with the US Food and Drug Administration (FDA) as Food Contact Substance Notification No. 1860. In accordance with the FDA’s instructions, we conduct compositional analysis, elution tests and toxicity tests on thin films to confirm safety,” Kinoshita maintains.
Moreover, treated bottles are recyclable, further reducing their environmental impact.
These credentials combined scored Kirin a WorldStar Packaging Award in the Beverage category, as well as recognition from the Dow Packaging Innovation Awards 2020.
Commercialization considerations
The technology is not currently applied to Mercian products, Kirin Holdings’ wine producing arm, but is in the process of commercialization.
“The challenge was to find a combination of feedstock gas and hot wire material that would provide both high gas barrier performance and thin film stability,” explains Kinoshita.
“To make it commercially viable, we worked hard to develop mass production technology for the raw gas and to improve the durability of the hot wire.”
The technology uses special ceramic rods to form a thin film on the bottle’s inner surface to prevent oxygen permeation.Technically, the new film technology can be used for all types of beverages. However, Kinoshita affirms it is “not necessary” for beverage containers where gas barrier properties are not required from a cost perspective.
In terms of expenses, the film formation cost per bottle is the same as that of conventional thin film gas barrier technology.
“On the other hand, the film-forming equipment is simpler than that of conventional technology, so the initial cost of introduction can be reduced,” notes Kinoshita.
Aiming for future applications outside of alcoholic beverages, Kirin plans on collaborating with external partners to explore the technology for seasonings, food and cosmetic containers.
Health science fields, such as cell culture materials, are also in the pipeline, adds Kinoshita.
By Anni Schleicher
