How to avoid folds in zipper bags?

Zipper bags are a very large form in the category of flexible plastic packaging. They have the advantages of easy access and repeated use. From the perspective of packaging manufacturers, the production process requirements of bags without zippers are still very high. . Today we will analyze the wrinkles that often occur in zipper bags.

There are two types of common problems in zipper bags: one is the partial delamination or surface wrinkles at both ends of the zipper; the other is the surface wrinkles at the seal between the zipper and the bag body.

Wrinkles at both ends of the zipper bag are sometimes closely related to the choice of zipper. When purchasing a zipper, you must pay attention to its melting point and shrinkage rate lower than or equal to the melting point and shrinkage rate of the composite film heat-seal layer, so as not to Wrinkles that occur when the melting point and shrinkage rate are seriously mismatched.

The cooling condition in the bag making process is also one of the important factors. If the deformed zipper can be sufficiently cooled before the bag making process is completed, the composite film that has completed the bag making process is in storage conditions. The possibility of continued heat shrinkage will be greatly reduced. If the heat-sealing layer and the zipper in the composite film bag that have completed the bag-making process are still in a molten state or viscoelastic state, then under storage conditions, the heat-sealing layer and the zipper will definitely undergo a certain degree of heat shrinkage. Then a corresponding degree of surface wrinkle phenomenon occurs. Therefore, the cooling surface temperature of the bag making machine becomes one of the important factors affecting the appearance quality of the composite bag.