Silica-coated for improved gas barrier performance of PET films earlier than Diamond-like carbon films. In the early 80 's of the last century, is through physical vapor deposition and chemical vapor deposition of silica coated in a manner. However, Silicon oxide films with brittle, the mechanical strength of the PET in order to obtain lasting requires complex processing. In recent years, Diamond-like carbon films (amorphous hydrocarbon) coating on PET surface (Figure 1) on some of the products in the market have emerged, gas barrier performance of PET bottles have been greatly improved.
, Diamond-like carbon coating process
Diamond-like carbon coating by plasma chemical vapor deposition (PCVD), as shown in Figure 2. In vacuum condition by plasma-CVD technology in PET bottles are very thin DLC coating on the inner surface. Coating process is as follows: first of all, put the bottle in a vacuum chamber for vacuum processing and injecting C2H2 gas, variable-frequency high-voltage plasma under the action of hydrocarbons, and ions and free radicals in PET bottles deposited, get the DLC coating.
Second, the characteristics of diamond-like carbon coating
DLC film contains large of hydrogen, so has very good of bond and anti-fissile capacity, while makes PET bottle has following advantages: gas high barrier performance, barrier oxygen and carbon dioxide, guarantee soft drinks of quality; flavor barrier performance, block bottle and packaging real Zhijian of migration and adsorption process, makes soft drinks keep original of flavor; UV barrier performance, has absorption UV of function, avoid soft drinks by UV of effect; chemical inert, not and other material reaction, has chemical stability ; To recycle while maintaining the existing advantages of PET bottles.

Barrier properties of DLC coated PET bottles have been greatly improved, as shown in table 1. But PET bottles barrier properties and temperature changes have a great relationship. When temperature rises, coated and uncoated PET bottle has a low barrier properties, suggesting that despite the thermal stability of the coating material, but the thermal motion of molecules affect the gas barrier properties of PET bottles.
The development of DLC coated PET bottles
DLC coated PET bottles from the market of the future development needs, focusing on technology development and improvement. Prospects are very bright, has great potential in the market, holds an estimated PET10% of the market, about 30 billion, widely used in the packaging of soft drinks, including tea, juices, carbonated beverages, and so on. Currently in Japan used for beverage packaging, have appeared on the market in 2005 and has 50 million market. As the soft drinks market gradually expanded, DLC coated PET bottles will be further applied.