What causes bellows bags to tear easily? How to deal with it?

Bellows bags are made by folding the two side edges of a normal flat bag into the bag body, changing the originally oval opening into a rectangular one. Because after folding, the sides of the bag resemble bellows leaves, but are closed, this type of packaging bag is named bellows bag. Packaging bag Named bellows bag. Among many packaging bags Bag types, because the internal space of the bellows bag is larger than other three-side sealed bag types, and the price is lower ， many customers like to customize this type of packaging bag. However, if the bellows bag breaks, it will not only affect the quality of the packaging bag, but also directly affect the product quality. How to solve this problem? Below, Shunxingyuan Packaging, a professional flexible packaging manufacturer, will analyze the causes and solutions of bellows bag breakage based on its rich experience in producing packaging bags.

There are two production processes for bellows bags, one is the middle-sealed bellows bag; the other is the four-side sealed bellows Bag bag. These two processes have a common process control point that needs attention: Bellows position 。 

1. Analysis of breakage causes

There is a step-like position at the junction of the bellows position and the horizontal sealing position, that is, the two sides of the bellows only have two layers of material heat-sealed at the horizontal sealing position, while the horizontal sealing edge of the bellows position will have four layers of film to be heat-sealed Therefore, a step-like connecting edge will appear at this position. The heat-sealing mold is basically on a horizontal plane. Therefore, under the same pressure and temperature, as shown in Figures 1 and 2, the pressure on the horizontal seal between the dashed lines is relatively small while the pressure outside the dashed lines on both sides is relatively large, especially the transition from two layers to four layers junction The stress is relatively larger, so this type of packaging Bag Bag type will form a stress point many times the packaging bag breaks from here.

2. Solutions

（ 1 ） Improve raw and auxiliary materials

This improvement mainly improves its physical properties from the raw materials, such as selecting materials with anti-cracking, tensile, wrinkle resistance, increased flexibility, increased toughness, and improved physical and mechanical properties to reduce the probability of the bellows line being damaged during production. Or through increasing the material thickness to improve. At the same time, you can also use adhesive with good toughness to enhance wrinkle resistance and improve packaging Bag resistance to breakage and kneading.

（ 2 ） Improve material structure

Bellows bags generally choose BOPP/CPP, PET/PE, BOPP/PE, NY/PE, PET/AL/PE, NY/AL/PE, PET/NY/PE structures When a certain structure is relatively weak, materials with better physical properties can be used as substitutes, or the number of structural layers can be increased to improve the overall Packaging bag strength. Considering the mechanical properties such as the anti-bending property and mechanical tensile property of the fabric, NY is better than PET, and PET is better than BOPP Of course, if NY is used to replace PET, the price will definitely increase. bellows bag material properties. This is also a good way, but price the cost will increase a lot. When increasing the number of material layers, carefully evaluate the changes in performance brought about by the increase in materials.

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