Flexible packaging materials such as plastic films and sheets have the advantages of low cost, light weight and convenient processing, and are widely used in packaging various products of daily use, such as food and medicine. According to different technical and application needs, the barrier properties of flexible packaging materials such as plastic films and sheets are different. Sometimes high barrier property is required to block oxygen to prevent oxygen ingress, and sometimes low barrier property with better oxygen permeability is required To facilitate the exchange of oxygen inside and outside the package. The air permeability of flexible packaging materials such as plastic films and sheets directly affects the quality of their packaging products.
Currently there are pressure method (difference pressure method and equal pressure method), concentration method, volumemethod, gas chromatography and heat conduction method to do the air permeability test of plastic film. According to different test methods, various types of air permeability testing equipment for plastic films have been developed at home and abroad. Among them, the differential pressure method is the primary method in the air permeability test of plastic films. The international test standards for film gas permeability based on the differential pressure method include ASTM D1434, ISO15105-1, ISO 2556-2001, JIS K7126, etc. The standards implemented in my country are IOS1038-2000, IOS 5453- 1997 , etc., fully automatic The fabric air permeability meter is a test instrument, and the manufacturer is QINSUN Welcome customers who have questions.
During the test, the vacuum pump evacuates the vacuum on the low pressure side of the test device to below 27Pa. The leak from the system has a cavee influence on the test results. The smaller the leakage, the more accurate the test results. Conversely, the rougher the test results, the higher the barrier properties of the plastic film.
In the case of a particular sealing material and sealing technology, it will affect the test device The most important factor of the sealing performance is the sealing structure. In order to ensure that the temperature of the test environment meets the requirements of the national standard, in the case of a certain temperature sensor, it is necessary to adopt an appropriate constant temperature control technology. At present, the gas permeability testing device uses a single-layer sealing structure, which has the advantage of simple structure, but the disadvantage is that the gas leakage is relatively large and the pressure change will be relatively large. high barrier film, the sealing performanceies are difficult Achieve technical application requirements.
This article analyzes the research status of the air permeability test device based on the differential pressure method, and puts forward several factors affecting the performance of the air permeability test device, and should address the problem of air permeability test of high barrier film reasonably. With the current capabilities of vacuum technology and sealing technology, without a sharp increase in testing costs, the air permeability testing device that meets the national standard requirements and can directly and accurately test high barrier films can be developed by improving the design of the single seal structure change and suitable constant temperature control technology.