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When Printing Complex, Resulting In Broken Bags Rate Is So High The Culprit Is It!
Nov 25, 2016

Effect of heat sealing process are as follows:

1, heat seal material type, thickness and quality of heat seal strength have a decisive impact. General packaging commonly used heat sealing materials have CPE, CPP, EVA, hot melt adhesives, and other Ionic resins co-extruded blend films. Heat sealing layer thickness of material between 20~80 μ m, special cases also have 100~200 μ m. With a heat seal material, the heat seal strength increases with heat seal thickness. Cooking bag heat seal strength of General requirements of 40~50 Newton, so the heat sealing material thickness should be above 60~80 μ m.

2, heat seal temperature has a direct effect on the heat seal strength. The melting temperature of a variety of materials, directly determine the composite minimum heat seal temperature. In the production process, due to heat stress, bag-making speed and the thickness of the substrate, and many other effects used heat sealing temperatures tend to be higher than the melting temperature of sealing material. Heat sealing with less stress, hot temperature higher speed faster, composite membrane surface in thicker materials requiring higher the sealing temperature. Heat seal temperature if below the softening point of sealing material, regardless of how to increase the pressure or extended heat sealing time is unlikely to make heat seal layer true seals. But if the heat seal temperature is too high, and extremely easy to damage sealing material welding melt, producing "undercut" phenomenon, greatly reduce the heat seal strength and sealing bag impact resistance.

3, in order to achieve ideal heat seal strength, a certain amount of pressure is essential. For lightweight packaging, sealing pressure is at least 2kg/CM22, but increase as the total thickness of the composite film. If hot seal pressure insufficient, two layer film Zhijian to reached real to fusion, to collection local hot seal bad, or to catch do clip in weld middle of bubble, caused virtual welding; certainly, hot seal pressure also not more big more good, should to not injury welding side suitable, because in high of hot seal temperature Shi, welding side of hot seal material has in half melting State, too big of pressure easy squeeze go part hot seal material, makes weld edge formed half cut State, weld sent crisp, hot seal strength reduced.

4, sealing time is mainly determined by the speed of bag making machine. Sealing time also affect weld seal strength and appearance as a key factor. The same sealing temperature and pressure, long sealing time, heat sealing layer fusion better, combined with stronger, but sealing time too long, easy weld wrinkling, affect the appearance.

5, sealing weld if cooling is not good, will not only affect the appearance of the weld seam roughness and heat sealing strength of a certain degree of influence. Cooling process is through a certain amount of pressure, just with a lower temperature after the heat setting of the weld, eliminating stress concentration process. Therefore, the pressure is not enough cooling water circulation is impeded, the cycle is not enough, the water temperature is too high, or cooling time will cause poor cooling, heat seal side up, reduce heat seal strength.

6 more times, heat sealing, seal strength higher. Longitudinal sealing depends on the number of vertical rods length and bag lengths of; number of lateral heat seal machine group is determined by the number of lateral heat seal device. Good heat sealing, at least twice or more requires heat sealing. General bag hot knife with 2 groups, and hot knife position higher degree of overlap, sealing the better.

7, the same structure and thickness of the laminate, composite high Peel strength between layers, heat seal strength is greater. For the composite of products with low Peel strength weld failure is often the first layer weld composite membrane peeling, caused by internal heat sealing layer independent bear damage tension, and surface materials lose reinforcement, heat sealing strength of welds is greatly reduced. If the peeling strength of the composite is large, is not edge-welding layer of peeling, measured by the actual heat seal strength is much greater.