Test Analysis of Oxygen Blocking Performance of Packaging Containers (I)

In the 1980s, almost all types of packaging for carbonated soft drinks, hot-filled beverages, mineral water, edible oils, flavorings, alcoholic drinks, jams, etc., were used in the domestic food market. Recyclable glass bottles are now used. A wide range of new materials such as plastic bottles, two-piece cans, three-piece cans, and paper-plastic aluminum composite flexible packaging have been replaced. In particular, the market demand for PET plastic bottles has grown very fast and now accounts for a major share of the domestic beverage packaging market. Oxygen barrier performance of the outer packaging directly affects the shelf life of the product, and the requirements for standardized testing of its oxygen permeability testing are very urgent. The traditional oxygen permeability test method is to test the material into a sheet, and after the bottle is formed, the thickness of the bottle body is different and the material properties are changed during the production process. The data for the sheet test can represent Oxygen permeation performance of the entire container, the manufacturer is skeptical, industry experts also believe that only with partial oxygen permeability to assess the entire container's oxygen barrier performance, point of view is not scientific, the plastic container product oxygen permeability test has become the current industry A big problem.

1 Limitations of Container Barrier Testing

Uncertain container size. With the development of society and the advancement of manufacturing processes, large and small container bottles on the market can be seen everywhere. The size, size, size and surface area of ​​the containers are difficult to be consistent, which brings certain difficulties to the air permeability testing of the containers.

Large differences in container mouth. There are various kinds of containers, and the style of the container mouth is also varied. The shape of the container mouth also shows a tendency of change with the development of the market. Because the change of the size and shape of the container mouth significantly affects the fixing and sealing of the container, the connection between the container mouth and the equipment is a major problem in the testing process.

Test the connection and sealing between the chamber and the oxygen permeability meter. There are mainly three kinds of test chambers: 1. Do not use the test chamber, the test can only be conducted in the open state (oxygen concentration in the test environment is the oxygen concentration of the laboratory environment); 2. Use transparent plastic bags as the test chamber, set Sealed on the outside of the container sample, this method is difficult to achieve the oxygen flow cycle, the oxygen concentration in the bag is subject to certain restrictions, it is also easy to cause the container mouth seal is not strong; 3. Use high barrier material made special test The chamber is separated from the container and sealed. The sealing effect is good and oxygen circulation can be achieved.

In addition, the temperature environment of the laboratory is relatively high. First, because of the nature of the sensor, the oxygen permeability test itself is greatly affected by the laboratory environment.

2 Development of foreign container barrier test

For the problem of how to solve the container barrier test, the global barrier research institutions and experts have done excessive discussions. At present, the national standard has no clear provisions on the testing standards in this area. Below, we use the ASTM F 1307-02 standard as For example, look at the development status of the container barrier test abroad.

ASTM F 1307-02 Standard Test Method for Oxygen Transmission Rate Through Dry Packages Using a Coulometric Sensor, Its Test Principle and Coulomb Method Oxygen Permeability Test Completely the same.

This test method uses Coulomb sensors and related equipment in a similar manner to test method D 3985. Oxygen transmission rate (O2GTR) is determined after the sample is fixed on the test device and equilibrated in the test environment. The fixed sample was to meet the conditions for the inner side of the package to be slowly purged with a stream of nitrogen and the outer side exposed to an environment where the oxygen concentration was known. )

The method of preparation of the equipment-connected packaging for testing depends on the shape, type, and test object of the packaging. As long as 100% oxygen is used to establish the test gradient, care should be taken not to pressurize the oxygenated vessel structure. (The partial pressure of oxygen should be equal to atmospheric pressure.)

The fixing method shown in Fig. 1 is applicable to bottles, thermoformed plastic cups, and barrels. Another type of fixing that does not cover the transparent outer bag can be used to fix a soft bag.

Figure 1. Typical Fixing Methods for Plastic Bottles and Buckets (To Be Continued)