PET bottle has been developing rapidly since they came out

The characteristics of PET bottle

Compared to other plastic packaging materials, PET is the best materials of soft drinks packing. This is because the PET has high melting temperature, strength and transparency. It also has good gas barrier properties and flavor barrier properties. What's more, its cost is low and it is easy to be shaped. At the same time, it is environmental and recyclable.

However PET bottle is still unable to meet the special requirements of some drinks, such as hot drinks and some soft drinks. Using PET in packing beer, juice and some soft drinks, it can't meet the packaging requirements to the barrier property of oxygen, carbon dioxide, water vapor and flavor, and it will affects the quality of these products. Improving the barrier performance of PET to oxygen, carbon dioxide has attracted public attention. Using some composite of PET and some materials with good barrier properties is the frequently-used method now.

The coating processing of PET bottle

In order to guarantee the quality of the soft drinks, it must avoid the seepage of gas happening in plastic bottle. This needs to choose those packaging materials which have small gas permeability, and we often call them high barrier property packaging materials. There are four ways to improve gas barrier property of PET below:

1. adopting the multi-layer co-extrusion technology

2. Surface coating processing

3. Adding some gas capture agent

4. Blending with other materials which have good gas barrier property

The multi-layer co-extrusion technology has come true now, but it works not so well, and its cost is high. Compared to this, surface coating processing is a new way to improve the gas barrier properties of PET. It is able to get a thin membrane to prevent effectively gas molecules going through the PET bottle wall. And at the same time, it can solve the problem of recycling.

The coating material now used has passed the test of practice, and some like diamond carbon material (DLC) and oxidation silicon material are very popular. Using Silicon oxide coating to improve the gas barrier property of PET film is earlier than diamond carbon membrane. But the silicon oxide film is brittle, and it needs relative complex processing to obtain lasting mechanical strength. In recent years, the appearance of the diamond carbon film makes huge improvement on the gas barrier property of PET bottle. It also promotes the plastic products greatly.