Kirin Holdings Co., Ltd. of Japan, in collaboration with Mitsubishi Chemical Corp., developed a new thin film deposition technology for PET Bottles—a thin film deposition system for high-performance PET bottles with high transparency, gas barrier, and stability when interacting with neutral aqueous solutions. This was notably impossible with previous PET thin-film gas barriers for bottles, according to the company. The innovation is created through a process that breaks down raw material gas to construct the colorless, transparent film on the inner walls of a PET bottle, and it is designed to provide cleaner, more efficient energy consumption and reduce product waste.
Applications for this method include use with beer and carbonated drinks, in order to prevent carbonic acid from being release from the liquid, through the PET. It also could be used with beer and juices which are prone to oxidative degradation through untreated PET. Another material, EVOH as a laminate on the PET, could potentially be used to accomplish the same task. But Kirin’s Leilei Wang tells Packaging World that EVOH, by comparison, is expensive, and limited in use, especially for PET beverage bottles. The Kirin film deposition is a more economical solution that accomplishes the same effect.
Wang describes the process that is used for the film deposition inside the PET bottle: “For our dedicated PET bottle hot wire CVD film deposition device, we devised a vacuum chamber to house PET bottles. A gas is supplied to the vacuum chamber that enters and fills the PET bottle, and hot wire is inserted along the center axis of the bottle. In the vacuum state, the hot wire is heated to a temperature at which the raw material gas is broken down, to create a thin film gas barrier,” she says. “The technology enables us to deposit unique, thin film—composed of silicon, oxygen, carbon, and hydrogen—evenly on the inner surface of the PET bottle.”
The raw material gas is called vinylsilane, an organosilicon compound with chemical formula CH2=CHSiH3. It is a derivative of silane (SiH4). The technology to radicalize gas comes out of the semiconductor industry. The entire system accommodates 12 bottles per minute, and the deposition rate is 35 seconds/bottle, and the Kirin deposition device has six chambers.
The process and food-contact film are approved by FDA (Food and Drug Administration). Kirin also obtained approval from the Japanese recycling industry, so it can recycled with PET, according to the company.
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