There are generally two types of leakage of flexible packaging products : one is the inevitable leakage caused by the design and structure itself. This leakage can be solved by changing the design and structure of the packaging product; the other is due to the flexible packaging product Leaks caused by defects generated during manufacturing, transportation, etc. This kind of leakage can be solved by adjusting without changing the design and structure.
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1. The heat sealing temperature is not enough
The same packaging material requires different heat sealing temperatures at different heat sealing parts, different packaging speeds require different heat sealing temperatures, different packaging temperatures require different heat sealing temperatures, and packaging equipment requires vertical and horizontal sealing. Different, the same heat sealing mold, the temperature of different parts may also be different, these are issues that must be considered in packaging. For heat sealing equipment, there is also a problem of temperature control accuracy. At present, the temperature control accuracy of domestic packaging equipment is poor, generally with a deviation of ± 10 ℃, that is, if the temperature we control is 140 ℃, the actual During the packaging process, the temperature is between 130 ℃ and 150 ℃. The reliable method is to sample at the lowest temperature point in the temperature range, and continuous sampling should be performed so that the sample can cover all parts of the mold in the vertical and horizontal directions.
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2. Poor thermal adhesion strength
Note: hot tack strength ≠heat seal strength! The heat sealing strength refers to the sealing strength of the flexible packaging bag after heat sealing and cooling, and the hot tack strength refers to the adhesive strength of the packaging bag when the sealing part is not cooled after heat sealing.
When using vertical bags for automatic packaging, the filling operation is performed when the horizontal sealing is completed and the sealing portion has not been cooled. When the contents fall from a certain height, an impact force will be generated on the horizontal sealing portion. If the force is greater than the sealing The thermal adhesive strength of the parts will be detached again, and the bag will break when it is serious.
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3. Poor puncture resistance
If the flexible packaging bag is punctured to form internal and external micropores, it will cause the vacuum packaging to fail, resulting in broken bags and leakage. Several common phenomena of piercing the bag surface are as follows.
( 1 ) It is punctured by the edges and corners of the packaging bags. For this purpose, the packaging bags with higher hardness should be rounded.
( 2 ) It is punctured by the sharp corners of the contents of the packaging bag. For this, materials with good puncture resistance, such as BOPA , PE , CPP, etc. , should be selected .
( 3 ) It is pierced by the crystal point impurities in the inner layer film or causes the barrier layer material to form cracks. During the filling of the packaging, the sealing position of the packaging material is often contaminated by the packaging, and the pollution is generally divided into liquid pollution and dust pollution. Solving the problem of contamination of the sealing part can be solved by improving the packaging equipment and using anti-pollution and anti-static heat sealing materials.
( 4 ) During the bag-making or packaging process, it is pierced by the sharp corner of the edge of the sealing knife.
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