In recent years, with the rapid economic development, more and more disposable money in the hands of residents, people's consumption concept is also changing. For the food industry, in the past, food manufacturers paid more attention to the price, because the lower the cost, the greater the market competitiveness, because most consumers only price, but now it is different, people's thinking has changed, convenient products are more popular. For example, for condiments in the past, simple packaging bags can meet the demand, but now most of the condiments have been added with suction mouthpieces or zippers, and convenient packaging is becoming more and more popular.
Zipper is a commonly used form in packaging, refers to the packaging bag that can be repeatedly sealed by pressing the zipper, with polyethylene (LDPE) and high pressure linear polyethylene (LLDPE) by blowing film forming, hot mechanism bag, which zipper bag is often formed at a time, after the filling or taking out, through the convex edge and groove at the opening, The plastic film bag can be sealed and opened repeatedly. Common materials include PE,EVA,PO, multi-layer composite zipper bag and so on.
However, in the production process of zipper bag, it is easy to encounter the problem of composite film folds around the zipper, which affects the aesthetics of the bag and its service life. Today, we will analyze the causes and ways to avoid wrinkles in zipper bags.
There are two common problems in zipper bags: one is the local layer or surface wrinkles at both ends of the zipper; The other is the surface fold of zipper and bag body sealing.
The folding at both ends of the zipper bag is sometimes closely related to the choice of the zipper. When choosing the zipper, we must pay attention to the melting point and shrinkage rate of the zipper is lower than or equal to the melting point and shrinkage rate of the composite film heat sealing layer, so as to avoid the folding phenomenon due to the serious mismatch between the melting point and shrinkage rate.
In the bag making process cooling conditions are also one of the important factors, if the deformation of the zipper can be fully cooled before the completion of bag making processing, the composite film wow crocodile has completed bag making processing in storage conditions will greatly reduce the possibility of heat shrinkage.
If the heat sealing layer and the zipper in the composite film bag which has been finished bag-making processing are still in the molten state or viscoelastic state, then, under storage conditions, the heat sealing layer and the zipper will have a certain degree of thermal contraction, and then produce the corresponding degree of surface folding phenomenon. Therefore, the surface temperature of bag making machine cooling becomes one of the important factors affecting the appearance quality of composite bag.
