Test of k-coating film for different gas barrier properties

Abstract: the barrier performance of different gases is one of the key test performance indexes of k-coating film In this paper, the barrier properties of k-coating film to oxygen and nitrogen are tested by vac-v2 pressure difference gas permeameter, which is the principle of pressure difference method The test principle, equipment parameters, application scope, test process and other contents are introduced, providing reference for the test and research of k-coating film to gas barrier performance Key words: oxygen permeability, nitrogen permeability, oxygen resistance, barrier performance, differential pressure gas permeameter, k-coating film, k-film, PVDC coating film 1, meaning PVDC (polyethylene terephthalate) as a high barrier material, is commonly used for coating on poor barrier PE, BOPP, BOPET, PA and other film surfaces to improve the overall barrier performance of the film The film formed after coating is referred to as k-film (i.e k-coating film), commonly including kPa, kpet, Kopp, KPE, etc Due to its good barrier performance, k-film can be used in the form of single-layer film or composite film in the food packaging of pastry, candy, biscuit and so on Due to the different types and packaging forms of packaged products, the barrier requirements for k-film materials are different, such as for oxygen sensitive food and inflatable packaging food, which have higher barrier to oxygen and nitrogen; in addition, the different molecular structure of gas also determines the different permeability of different gases in packaging Therefore, the test of different gas barrier performance of K film can further verify whether its barrier performance can meet the quality requirements of the packaged products 2 In this paper, a kind of k-coated monolayer film is used as the test sample to measure the oxygen and nitrogen transmittance 3 At present, there are two methods to measure the oxygen permeability of packaging materials: differential pressure method and isobaric pressure method Only differential pressure method can be used to measure the nitrogen permeability Therefore, this paper chooses the pressure difference method to test the barrier performance of the samples to oxygen and nitrogen respectively The test process is based on GB/T 1038-2000 "test method for gas permeability of plastic film and sheet" 4 In this test, vac-v2 differential pressure gas permeameter is used as the testing equipment, which is independently developed and produced by Jinan Languang Electromechanical Technology Co., Ltd 4.1 test principle the pressure difference method is to realize the gas permeation from the high pressure side to the low pressure side through the pressure difference on both sides of the sample, and to monitor the pressure change on the low pressure side by using the pressure sensor Firstly, the test chamber of the equipment is divided into upper and lower parts by using the clamped sample, and then the test gas with certain pressure is filled into the upper chamber The lower chamber forms a low-pressure environment by vacuuming, and the test gas penetrates into the low-pressure chamber through the sample According to the change of the pressure of the low-pressure chamber detected by the pressure sensor with the permeability time, the permeability parameters such as the gas permeability of the sample are calculated Fig 1 application scope of vac-v2 pressure difference gas permeameter 4.2 (1) this equipment is specialized in testing gas permeability, permeability coefficient, solubility coefficient and diffusion coefficient of various film and sheet samples at various temperatures Film type includes all kinds of plastic film, paper plastic composite film, CO extrusion film, aluminum coating 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) The equipment can also be extended to the air permeability test of aerospace materials, paper and cardboard, paint film, fiberglass cloth, fiberglass paper, cosmetic hose sheet, various rubber sheets and other materials (3) This equipment is suitable for the transmittance test of various gases, such as oxygen, nitrogen, carbon dioxide, helium, air, etc (4) This equipment can meet many national and international standards, such as GB / T 1038, ISO 15105-1, ISO 2556, ASTM d1434, JIS k7126-1, ybb00082003, etc 4.3 equipment parameters 0.05 ~ 50, 000cm 3 / (M 2 · 24h · 0.1MPa), the vacuum resolution can reach 0.1pA; the temperature control range is 5 ℃ ~ 95 ℃, the temperature control accuracy is ± 0.1 ℃; the humidity control range is 0% RH, 2% RH~ 98.5% RH, 100% RH, humidity control accuracy is ± 1% RH, which can meet the testing needs of customers under different test conditions; there are three completely independent test chambers, which can test three identical or different samples at the same time; data fitting at any temperature can be carried out to easily obtain the test results under extreme test conditions; after reform, the equipment can also support the testing of toxic gas, flammable and explosive gas Test; provide standard membrane for rapid calibration to ensure the accuracy and universality of test data; support Lystem TM laboratory data sharing system to manage test results and test reports in a unified way 5 Test process 5.1 oxygen transmission test (1) use a sampler to cut three samples with a diameter of 97 mm from the sample surface (2) Apply a layer of vacuum grease around the three test chambers of the equipment, place a piece of filter paper in the test area, paste three samples on the three test chambers in turn, press gently, remove the air bubble between the sample and the test chamber, close the upper chamber and tighten it Fig 2 sample loading process (3) the equipment is connected to the oxygen source, the sample name, vacuumizing time, test temperature, humidity and other parameter information are set on the control software, click to start the test, turn on the vacuum pump, the equipment is tested according to the set parameters, and the test results are displayed after the test 5.2 the test equipment for nitrogen transmission shall be connected with nitrogen gas source, and other operations are the same as those in 5.1 6 The arithmetic mean values of the test results of three samples are taken for the oxygen and nitrogen permeation of the samples The oxygen and nitrogen permeation of the k-coating film samples are 7.935 cm 3 / (M 2? 24h? 0.1MPa) and 0.653 cm3 / (M2? 24h? 0.1MPa) respectively 7 Conclusion the high barrier property is the key to distinguish k-coating film from common film According to different applications, oxygen and nitrogen transmittance are the key performance indexes of k-coating films In this paper, the barrier properties of k-coated film samples to oxygen and nitrogen are tested by the principle of differential pressure method The nitrogen transmission of the samples is significantly lower than that of oxygen, which is related to the molecular diameter of the gas The test process is simple, the results are accurate and intelligent, and the equipment is easy to operate Jinan Languang mechanical and Electrical Technology Co., Ltd is a high-tech enterprise specializing in the research, development and production of packaging testing equipment and packaging testing services The vac-v2 differential pressure gas osmometer used in this paper is one of many independently developed equipment, which can also be used to test the permeability of carbon dioxide, helium, air, sulfur hexafluoride and other gases In addition to gas transmission, Labthink's existing equipment can also test the water vapor transmission, tensile property, puncture strength, tear strength, impact strength, friction coefficient, heat sealing performance, thickness, total migration, solvent residue and other performance indexes of k-coating film The more you understand, the more you trust! 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