Abstract: With the diversified development of packaging forms, the types of gases in direct contact with packaging increase, and the barrier properties of packaging materials to different gases are important factors that affect the quality of packaging. This paper analyzes the barrier properties of BOPP / CPP films against oxygen and nitrogen, analyzes the barrier properties of packaging materials to different gases, and describes the test principle, test process, equipment parameters and scope of application, etc. The gas barrier performance provides a reference. Keywords: oxygen transmission rate, nitrogen transmission rate, BOPP / CPP, packaging materials, barrier properties, differential pressure gas permeation instrument 1. Significance With the increase of product types and the advancement of packaging technology, there are more and more packaging forms of products, such as vacuum packaging, nitrogen-filled packaging, modified atmosphere packaging, etc. For these forms of packaging, the barrier properties of packaging materials against gas It is an important factor that affects the packaging effect. If the barrier property of the packaging material is poor, and the amount of gas exchange between the inside of the package and the environment is large, it will cause the content of the gas component in the package to change, which will affect the quality assurance effect of the package. Taking modified atmosphere packaging as an example, modified atmosphere packaging maintains the appearance and quality of products by controlling the proportion of different gas contents inside the package, but the same packaging materials have different barriers to different gases, which is different from the size and size of gas molecules. It is related to the compatibility of packaging materials. Generally speaking, the smaller the gas molecule, the better the compatibility with the material, and the easier the gas penetrates into the material, that is, the higher the gas permeability. This difference in gas transmission rate is likely to cause a change in the proportion of gas inside the package. Therefore, through comparative analysis of the barrier properties of different gases, the development and selection of packaging materials with appropriate barrier properties are of great significance to ensure that the packaging will exert its quality assurance effect. 2. Test basis The detection methods of gas permeability include two test principles: differential pressure method and equal pressure method. Limited by the type of sensor and the test principle, the equal pressure method generally can only measure the oxygen permeability. In this paper, the differential pressure method can be used to test different sample pairs. The gas barrier performance is based on the standard GB / T 1038-2000 "Test Method for Gas Permeability of Plastic Films and Sheets, Differential Pressure Method". 3. Test samples The sample selected for this test is a BOPP / CPP film composited by dry method, and the oxygen permeability and nitrogen permeability of the sample are tested respectively. 4. Test equipment The test equipment used in this article is the VAC-VBS differential pressure method gas permeameter, which is independently developed and produced by Jinan Languang Electromechanical Technology Co., Ltd. Figure 1 VAC-VBS differential pressure method gas permeation instrument 4.1 Test principle The differential pressure method refers to the method of maintaining a certain pressure difference between the two sides of the sample during the test and obtaining the gas permeability of the sample by testing the change in pressure on the low pressure side. The specific implementation process is that after the sample is clamped on the equipment, the test chamber is divided into upper and lower chambers, and the upper and lower chambers of the equipment are evacuated to a certain vacuum degree, and then the upper chamber is filled with a test gas of a certain pressure To maintain a certain pressure difference between the upper and lower chambers, the gas in the upper chamber penetrates into the lower chamber through the sample under the effect of the pressure difference, and the gas permeability 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 testing the gas permeability of various films and sheets. Films include various plastic films, paper-plastic composite films, coextruded films, aluminized films, aluminum foil, aluminum foil composite films and other film-like materials; sheet materials include various engineering plastics, rubber, building materials and other sheet-like materials, such as PP Sheet, PVC sheet, PVDC sheet. (2) The equipment can also be extended to the air permeability test of materials for aerospace, paper and paperboard, paint film, fiberglass cloth, fiberglass paper, cosmetic hose sheet, various rubber sheets and other materials. (3) This equipment is suitable for the transmission test of various gases, such as oxygen, carbon dioxide, nitrogen, helium, air, etc. (4) This equipment meets many national and international standards, such as ISO 15105-1, ISO 2556, GB / T 1038, ASTM D1434, JIS K7126-1, YBB00082003. 4.3 Device parameters The test range is 0.1 ~ 100,000 cm3 / (m2 · 24h · 0.1MPa); three samples can be tested at the same time, the test result is the average value of the test results of the three samples; the sample temperature range is 15 ~ 55 ℃ , Temperature control accuracy is ± 0.1 ℃; Provide standard membrane for rapid calibration to ensure the accuracy and versatility of test data; Support LystemTM laboratory data sharing system, unified management of test results and test reports. 5. Test process 5.1 Cutting Six samples 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 ℃ for 48 h. 5.2 Oxygen transmission test (1) Apply vacuum grease evenly around the three test chambers, and place filter paper in the test area. Take three of the samples and paste them on the surface of the three test chambers of the equipment, remove the air bubbles between the sample and the test chamber, and clamp with the sample clamping device. Fig. 2 Sample clamping diagram (2) Set the sample name, test temperature, test humidity and other parameter information. Click the test option to start the test and turn on the vacuum pump. After the test, the device displays the test results. 5.3 Nitrogen permeability test The equipment is connected to a nitrogen gas source, and the nitrogen permeation amount of the sample is detected according to the steps in 5.2. 6. Test results The oxygen permeability of the BOPP / CPP film sample tested in this experiment was 779.0179 cm3 / (m2 · 24h · 0.1MPa), and the nitrogen permeability was 202.3561 cm3 / (m2 · 24h · 0.1MPa). 7. Conclusion From the test results of this paper, the measured oxygen permeability of the sample is significantly higher than that of nitrogen, which means that the amount of oxygen permeating through the packaging material under the same time and under the same conditions is more. This phenomenon is related to the molecular diameter of nitrogen Greater than the diameter of oxygen molecules. In addition, from the test process, the equipment is easy to operate, the test efficiency and intelligence are high, the test accuracy is high, and the test results are reliable, which can accurately reflect the barrier properties of the tested sample to oxygen and nitrogen. Jinan Languang Electromechanical Technology Co., Ltd. is a high-tech enterprise specializing in R & D, production and packaging testing services of packaging testing equipment. It has always been committed to providing customers with high-end, professional and precise testing equipment and accurate, efficient and intimate testing services. At present, the existing equipment includes gas permeability testing equipment, water vapor permeability testing equipment, intelligent electronic tensile testing machine, sealing tester, coefficient of friction tester, migration and non-volatile matter tester, tear tester, etc. Understand related equipment and testing service content, you can log in to view. The more you understand, the more you trust! Labthink looks forward to enhancing technical communication and cooperation with enterprises and institutions in the industry. Hair Stylers,hot air styler,hair stylers for short hair,hair dryer and straightener set,mini hair straighteners,air hair styler Ningbo Meirou Electric Appliance Co.,Ltd. , https://www.mrhaircurler.com
