The common problems of self-supporting bags, the solutions are all here!
With the development of the market, consumers have more and more diversified requirements. The stand-up bag has attracted the attention of many people with its unique shape and convenient characteristics. With the expansion of the stand-up pouch, its common quality problems have also been raised, mainly including leakage, uneven bag shape, asymmetric bottom seal, and size error. We will bring you the solution today.
1. Bag leakage
The reasons for the leakage of stand-up pouches mainly lie in the selection of composite materials and the strength of heat sealing.
1. Material selection
The choice of material has a great influence on the quality of the stand-up pouch. Appropriate materials can ensure the heat sealing strength of the stand-up pouch and the peeling strength between the material layers, and ensure that the stand-up pouch is not easily damaged. Therefore, the self-supporting pouch generally requires that the surface tension of the composite surface of the film must be greater than 38 dyn/cm; the low temperature heat sealing performance of the inner heat sealing film is better, and the surface tension of the heat cover must be less than 34 dyn/cm; In addition, it is necessary to use ink with good connection performance , High solid content and low viscosity adhesive, high purity organic solvent.
2. Heat sealing strength
Low heat seal strength is also the cause of the leakage of stand-up pouches. The heat seal strength is low, and the heat seal may be separated under the action of the external environment, resulting in leakage.
Therefore, the heat sealing temperature and heat sealing pressure should be set according to the characteristics of the stand-up pouch material. After the heat sealing is completed, a leak test should be carried out. The simplest and most practical method is to fill a certain amount of air in the bag, heat seal the bag mouth, put it into a basin containing water, and squeeze different parts of the bag by hand. , if no air bubbles escape, it means that the sealing and airtightness of the bag is good. In addition, the four-layer seal at the bottom of the stand-up pouch is the most critical part, and the heat-sealing temperature, heat-sealing pressure and heat-sealing time can only be determined after sufficient test and verification.
Second, the bag is not flat
Flatness is one of the indicators to measure the appearance quality of packaging bags. In addition to material factors, the flatness of the stand-up pouch is also related to factors such as heat sealing temperature, heat sealing pressure, heat sealing time and cooling effect. If the heat sealing temperature is too high, the heat sealing pressure is too high, or the heat sealing time is too long, the composite film will shrink and deform. Insufficient cooling will result in insufficient setting after heat sealing, and the internal stress cannot be eliminated, causing the bag to wrinkle. Therefore, the process parameters should be adjusted and the cooling water circulation system should work normally.
3. Poor symmetry
Poor symmetry affects not only the aesthetics of the bag, but also heat seal performance and stability. The main reasons for the poor symmetry of the stand-up pouch include uneven thickness of the composite film, ruffles, too little tension of the double floating rollers, improper control of the tension of the bottom material, and unstable rotation of some rollers. Therefore, if you want to avoid it, you need to take targeted solutions.
It can be corrected by adjusting the tension of the double floating rollers, checking and adjusting the relevant guide rollers (such as compensation rollers, deflection rollers, etc.), appropriately reducing the tension of the discharge, and increasing the waiting time during heat sealing.
In addition, the asymmetry of the bag shape is also related to factors such as photoelectric tracking, feeding, cursor design, rubber roller balance, and synchronization of stepper motors or servo motors. This problem should be solved according to the specific operation of different products and different bag making equipment.
4. Size error
The error in the size of the stand-up pouch is one of the common problems in production. Dimensional errors can affect customer satisfaction and even lead to returns. The reasons for the size error mainly include the excessive error of the bag length fixing system of the bag making mechanism, the inaccurate tracking of the electric eye, and operational factors, such as improper tension control, insufficient pressure setting of the film-feeding rubber roller pressure cylinder, etc.
To avoid dimensional errors, it is necessary to strictly control the operation, adjust the bag-making speed and the working state of the electric eye. Re-set the fixed-length system, adjust the rubber roller pressure, cylinder pressure and tension of each part.
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