Test Method for Oxygen Barrier Properties of Flexible Plastic Packaging Bags

Abstract: oxygen barrier properties is an important performance related to the quality of soft plastic packaging bags and an important basis for the selection of packaging materials. In this paper, the aluminum plastic composite film packaging bags for food packaging are used as test samples, and the OX2 / 230 Oxygen Transmission Rate Test System is used to test the oxygen permeability of the sample bags, and the test principle, conforming standard and test process are introduced, for the enterprise to test the oxygen barrier properties of flexible plastic packaging bags to provide a reference.

Keywords: oxygen barrier, oxygen transmission rate, oxygen transmission test system, soft plastic packaging bag, food packaging, aluminum plastic composite material

The oxygen barrier properties is expressed by the oxygen permeability. The high oxygen permeability of the soft plastic packaging bag indicates the low oxygen barrier properties. On the contrary, the low oxygen permeability means the high oxygen barrier performance. At present, the samples for the test of oxygen barrier properties of packaging materials are mainly divided into film / sheet and container. Soft plastic packaging bags are usually cut into film form for the test. The oxygen permeability obtained is the volume of oxygen that permeates the packaging materials per unit time and per unit area, which is convenient for the research, comparison and quality control of the material’s oxygen resistance. To get the overall oxygen permeability of packaging bags In addition, the test value of the film should be multiplied by the surface area of the packaging bag, which will enlarge the error of the result, especially for the packaging bag with irregular shape, such as stand up pouch, folding bag, suction nozzle bag, etc., because the area of the packaging bag is difficult to measure, it will generate greater error. In addition, for the packaging materials which are prone to creases, pinholes and are not resistant to flex on the surface, due to the existence of such defects as creases, the oxygen permeability of different parts of the packaging bag is different, and the overall oxygen barrier properties calculated from the oxygen permeability of the materials is not accurate. Therefore, if we want to evaluate the overall oxygen resistance of the soft plastic packaging bag, it is more accurate to directly test the whole bag for its oxygen transmission rate.

Standard

The testing methods of oxygen permeability are mainly divided into two kinds: isobaric method (coulometric method) and differential pressure method. This paper tests according to ASTM F1307 Standard Test Method for Oxygen Transmission Rate Through Dry Packages Using a Coulometric Sensor.

Sample

The test sample used in this paper is aluminum plastic composite film packaging bag for food packaging.

Test Instrument

In this paper, OX2 / 230 Oxygen Transmission Rate Test System is used as the test instrument, which is independently developed and produced by Jinan Labthink Instruments Co., Ltd.

Figure1  OX2 / 230 Oxygen Transmission Rate Test System

Test principle

Coulometer method is a quantitative test method for measuring oxygen permeates the sample by using a coulometric sensor. In this method, the concentration difference drives oxygen penetrating the sample. The specific process is that the pressure on both sides of the sample remains equal during the test. One side of the sample uses high-purity nitrogen as carrier gas and the other side uses high-purity oxygen. After the oxygen permeates to the nitrogen side of the sample, it is carried to coulometric sensor by nitrogen through the analysis, the oxygen permeability of the sample can be obtained. For packages and containers, the outside of the sample is high-purity nitrogen and the inside is high-purity oxygen.

Test process

5.1 Sealing the sample. Cut off one corner of one edge of the sample, insert the air inlet and outlet through the special sample holder into the sample from the cutting opening, and then seal the sample on the tray with quick fix adhesive.

Figure2 Sealing the sample

5.2 Mounting the sample. Clamp the specimen holder with sealed specimen on the equipment, and seal and bind the specimen and tray holder with sealed bag.

5.3 Running the test. Set the parameter information such as sample name, test temperature, test humidity and test mode, and click the “test” option to start the test. Turn on the air source and adjust the carrier gas flow and humidity.

5.4 Finishing the test. After the test, the instrument will automatically display the test value of oxygen transmission rate of the sample.

Test result

In this test, the arithmetic mean of the test values of the two samples is taken as the oxygen transmission rate of the aluminum plastic composite film for food packaging, and the result is 0.2346 cm³/(pkg·24h).

Conclusion

Good oxygen barrier performance is one of the key performance indexes of food packaging. In this paper, the principle of equal pressure method is used to test the oxygen transmission of an aluminum plastic composite film packaging bag for food packaging. From the perspective of the test process, the operation is simple, the instrument is highly automated, and the test precision is high. The test results can accurately reflect the oxygen barrier performance of the packaging bag. For aluminum-plastic composite film packaging bags, in addition to the oxygen barrier performance, the heat sealing strength, sealing performance and flex durability of the packaging are also important factors determining the amount of oxygen penetrating into the packaging in the environment. The corresponding testing instrument are auto tensile tester, leak and seal tester and flex durability tester. Please visit www.labthink.com for more information about the instruments. The more you understand, the more you trust! Labthink is looking forward to enhancing technical communication and cooperation with enterprises and institutions in the industry!