PET bottle surface barrier coating technology

The use of silicon oxide and other surface coatings to improve the barrier properties of PET films has been practically applied in the industry. People are also trying to improve the barrier properties of PET bottles by applying vacuum coating on the walls of PET bottles to meet the needs of beer packaging. However, due to poor coating strength, it has not yet been put into practical use.
Nissei ASB Machinery Co., Ltd. and Sidel of France actively promote the surface-coated PET beer bottle technology. The basic principle is to use plasma deposition surface coating technology to form a barrier layer on the inner wall of the plastic bottle.

This new technology, called the AC-TIS Barrier Layer (without a qualitative carbon-treated inner surface), converts acetylene to plasma by sending acetylene gas under vacuum into the bottle and then using microwave energy. The plasma moves in a bottle at high speed in an unordered manner. When high-energy ions hit the inner wall of the bottle, they sink into the surface of the inner wall and eventually agglomerate to produce a highly hydrogenated layer with a thickness of 0.1 μm. Forming a solid carbon film, the coating is easy to recycle and reuse, and its environmental protection is good. The barrier to O2 is 30 times higher than that of pure PET bottles, and the permeability to CO2 is increased 7 times. Comparable PET bottles extend the shelf life of beer by more than six weeks. The mobility of acetaldehyde in the bottle wall, which affects the taste of the beverage, is reduced by a factor of six. The Actis20, the first commercial device produced by Sidel, can process 10,000 PET bottles with a maximum capacity of 0.6L per hour. It is said that under the premise of satisfying the barrier performance of beer bottles, the cost is lower than that of glass bottles and aluminum cans. Therefore, the ACTIS technology is considered to be an ideal method for high barrier properties of PET bottles. Nissei ASB developed the DLC vapor deposition technology, and the specific coating process was carried out as follows: The stretched blow-molded bottles were arranged in groups of eight each into the paint booth of HBB-8, and then the air was drawn out. Vacuum state. A tube is used to introduce acetylene gas into the bottle through the bottleneck. A high-frequency current acts on the electrode. At this time, the coating chamber is an external electrode, and the acetylene tube is an internal electrode; acetylene is decomposed into ionized carbon and ionic hydrogen due to current discharge, and ionized carbon and ionized hydrogen are combined on the inner surface of the bottle. , Forming a fine coating.

This carbon-based coating by vapor deposition has a thickness of 20 nm to 40 nm, which is 20 times more gas-barrier than an ordinary PET bottle, 7 times higher in CO2 permeation resistance, and 8 times higher in anti-H2O permeability. The ability is also enhanced.