Abstract: With the diversification of packaging forms, the types of gases that are in direct contact with packaging increase, and the barrier properties of packaging materials to different gases are important factors affecting the quality of packaging. In this paper , the barrier properties of BOPP/CPP film for oxygen and nitrogen are tested and compared. The barrier properties of different materials are analyzed. The test principle, test process, equipment parameters and scope of application are described. The gas barrier properties provide a reference.
Key words: oxygen permeation, nitrogen permeation, BOPP/CPP , packaging materials, barrier properties, differential pressure gas permeation
1 , meaning
With the increase of product types and the advancement of packaging technology, more and more packaging forms of products, such as vacuum packaging, nitrogen filling packaging, modified atmosphere packaging, etc., for these forms of packaging, the barrier properties of packaging materials to gases It is an important factor affecting the packaging effect. If the barrier property of the packaging material is poor, the gas exchange amount inside the package and the environment is large, which will cause the content of the gas component in the package to change, which affects the shelf-keeping effect of the package. Taking modified atmosphere packaging as an example, the modified atmosphere packaging maintains the appearance and quality of the product by controlling the proportion of different gas contents inside the packaging, and the same packaging material has different barrier properties for different gases, which is related to the size of the gas molecules and It is related to the compatibility of the packaging material. Generally, the smaller the gas molecule, the better the compatibility with the material, and the easier the gas permeates into the material, that is, the higher the gas permeation amount. This difference in the amount of gas permeation is likely to cause a change in the proportion of gas inside the package. Therefore, through the comparative analysis of different gas barrier properties, the development and selection of packaging materials with appropriate barrier properties is of great significance to ensure the packaging to play its quality.
2 , test basis
There are two test methods for gas permeability measurement: differential pressure method and equal pressure method. Due to the type of sensor and the principle of testing, the equal pressure method can only test the oxygen permeation. In this paper, the differential pressure method can be used to test different pairs of samples. The barrier property of the gas is based on GB/T 1038-2000 " Phase Difference Method for Plastic Film and Sheet Gas Permeability Test Method ".
3 , test samples
The sample selected in this test was a dry-composited BOPP/CPP film , and the oxygen permeation amount and nitrogen permeation amount of the sample were respectively tested.
4 , test equipment
The test equipment used in this paper is VAC-VBS differential pressure gas permeation instrument, which is independently developed and produced by Jinan Languang Electromechanical Technology Co., Ltd.
Figure 1 VAC-VBS differential pressure gas permeation meter
4.1 Test principle
The differential pressure method refers to a method in which a certain pressure difference is maintained on both sides of the sample during the test, and the gas permeation amount of the sample is obtained by testing the change of the pressure on the low pressure side. The specific implementation process is that after the sample is clamped to the device, the test cavity is divided into upper and lower chambers, and a vacuum is applied to the upper and lower chambers of the device to a certain degree of vacuum, and then the test gas is filled into the upper chamber with a certain pressure. The upper and lower chambers are maintained at a certain pressure difference, and the gas in the upper chamber is infiltrated into the lower chamber by the pressure difference under the action of the pressure difference, and the gas permeation amount of the sample is obtained by testing the pressure change in the lower chamber.
4.2 Scope of application
(1) This equipment is suitable for gas permeability testing of various films and sheets. Films include various plastic film, paper-plastic composite film, co-extruded film, aluminized film, aluminum foil, aluminum foil composite film and other film-like materials; sheet materials include various engineering plastics, rubber, building materials and other sheet materials, such as PP Sheet, PVC sheet, PVDC sheet.
(2) This equipment can also be extended to aerospace materials, paper and paperboard, paint film, fiberglass cloth, glass fiber paper, cosmetic hose sheets, various rubber sheets and other materials for gas permeability testing.
(3) This equipment is suitable for the permeability test of various gases, such as oxygen, carbon dioxide, nitrogen, helium, air, etc.
(4) This equipment meets a number of national and international standards, such as ISO 15105-1 , ISO 2556 , GB/T 1038 , ASTM D1434 , JIS K7126-1 , YBB00082003 .
4.3 Equipment parameters
The test range is 0.1 ~ 100,000 cm 3 /(m 2 ·24h·0.1MPa) ; the test of 3 samples can be completed at the same time . The test result is the average value of the test results of 3 samples; the temperature range of the sample is 15 ~ 55 °C , temperature control accuracy is ±0.1 °C ; standard film is provided for rapid calibration to ensure the accuracy and versatility of the test data; support Lystem TM laboratory data sharing system, unified management test results and test reports.
5 , the test process
5.1 cutting
Six specimens with a diameter of 80 mm were cut from the surface of the BOPP/CPP film sample to be tested , and placed in a desiccator at 23 °C for 48 h .
5.2 Oxygen Permeation Test
(1) Apply vacuum grease evenly around the three test chambers and place filter paper in the test area. Wherein the three samples were taken at apparatus 3 attached test chamber surface, to remove air bubbles between the sample and a test chamber, and a sample clamping device.
Figure 2 sample clamping diagram
(2) Set the parameter information such as sample name, test temperature, test humidity, etc. Click the test option, the test starts, and the vacuum pump is turned on. After the test is over, the device displays the test results.
5.3 Nitrogen Permeation Test
The device is connected to a nitrogen gas source and the nitrogen permeation of the sample is measured according to the procedure in 5.2 .
6 , test results
The oxygen permeation amount of the BOPP/CPP film sample tested in this test was 779.0179 cm 3 /(m 2 ·24h·0.1MPa) , and the nitrogen permeation amount was 202.3561 cm 3 /(m 2 ·24h·0.1MPa) .
7 , conclusion
From the test results of this paper, the measured oxygen permeation of the sample is significantly higher than the nitrogen permeation amount, which indicates that the amount of oxygen permeating the packaging material under the same conditions and under the same conditions is more. This phenomenon is related to the diameter of the nitrogen molecule. More than the diameter of the oxygen molecule. In addition, from the test process, the equipment is easy to operate, the test efficiency and intelligence are high, the test accuracy is high, the test result is reliable, and the barrier performance of the tested sample to oxygen and nitrogen can be accurately reflected. Jinan Languang Electromechanical Technology Co., Ltd. is a high-tech enterprise specializing in R&D, production and packaging testing services for packaging testing equipment. It is committed to providing customers with high-end, professional and sophisticated testing equipment and accurate, efficient and caring testing services. At present, the existing equipment includes gas permeability detecting equipment, water vapor transmission detecting equipment, intelligent electronic tensile testing machine, sealing tester, friction coefficient meter, migration amount and non-volatiles measuring instrument, tearing instrument and the like . 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.
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