Traditional testing methods of package sealing

　　The traditional packaging tightness testing is usually destructive manual testing methods, such as electrolysis test, dye penetration test and bubble test. The main disadvantage of destructive testing is that it is unable to detect every packaged product, and it takes time and labor to detect.

　　1. Test method for rigid sealed packaging

　　The traditional methods for testing the tightness of rigid containers mainly include visual inspection, talcum powder method and sealing performance monitoring method. These three methods have applicability and obvious defects. Visual inspection is simple and convenient, but only applicable to obvious opening. The inspection of talcum powder is greatly affected by packaging shape and human factors, and its reliability is not high. Although the reliability of the detector is high, the sealed package is also damaged during the detection. There are many working links from drilling to resealing, which is not conducive to work. For packages with good sealing test results, the test process will produce many side effects.

　　2. Dyeing method

　　This method is usually applicable to the detection of composite bags with very little air content. The method is to take out the contents of the sample, wipe the inside of the sample, pour the test liquid (colored water solution with obvious color difference with the filter paper) into the sample, and seal the mouth. Place the sample on the filter paper for more than 5 minutes, and observe the leakage of test liquid from the sample. Then turn the sample over and test the other side.

　　It can be seen from this that the dyeing method can only detect whether there is leakage at the side of the flexible packaging. Since the original seal has been damaged, it is impossible to judge whether there is leakage at the original seal.

　　3. Bubble method

　　Bubble method is also called vacuum method or water decompression method. This method is usually applicable to the detection of composite bags with high air content. The specific methods can be divided into the following two: vacuum pump method and vacuum generator method. Because the vacuum formed by vacuum pump method is pulsating airflow, the vacuum of packaging and printing is unstable; Long vacuum forming time; The vacuum is difficult to maintain and the sealing performance is poor; Pointer pressure display, low accuracy. Therefore, it has been phased out.

　　The vacuum generator method is usually applicable to the detection of composite bags with high air content. Bubble method is to soak the tested sample in a liquid at a certain temperature, and observe whether there are bubbles on the surface of the sample in the immersion solution with a low power microscope or naked eye. The soaking solution is generally a liquid with stable performance and no damage to the product. The temperature used should be controlled within the tolerance range of the sample, otherwise it will lead to wrong detection. Sometimes, in order to improve the detection effect, the immersion solution is usually pressurized or decompressed.

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