Bag leakage
The main reasons for the leakage of stand up pouch are the selection of composite materials and the heat sealing strength.
Material selection
The selection of materials for stand up pouch is crucial for preventing leakage, with the aim of improving the peel strength between the outer and intermediate barrier layers, as well as between the barrier layer and the heat sealing layer material, and the heat sealing strength of the bag. Therefore, it is required that the surface tension of the composite surface of the film must be greater than 38dyn/cm; The low-temperature heat sealing performance of the inner layer heat sealing film is good, and the surface tension of the hot surface must be less than 34dyn/cm; In addition, it is necessary to choose inks with good connectivity, adhesives with high solid content and low viscosity, and organic solvents with high purity.
Heat sealing strength
The low heat sealing strength is also one of the important factors affecting the leakage of upright bags. When heat sealing, it is necessary to adjust the matching relationship between heat sealing temperature, heat sealing pressure, and heat sealing time. Especially, it is important to explore the heat sealing temperature of bags with different structures, as different types of plastic films have different melting points and heat sealing temperatures; The heat sealing pressure should not be too high, and the heat sealing time should not be too long to avoid the degradation of macromolecules. The heat sealing layer is cut by the heat sealing knife in a high-temperature melting state, resulting in a decrease in the sealing strength. In addition, the four layers of sealing at the bottom of the upright bag are the most critical parts, which need to be fully tested and verified before determining the heat sealing temperature, pressure, and time.
In the actual production process, leakage tests should be conducted on stand up pouch according to the different requirements of the content. The simplest and most practical method is to fill the bag with a certain amount of air, heat seal the bag mouth, place it in a basin containing water, and squeeze different parts of the bag with your hands. If no bubbles escape, it indicates that the bag has good sealing and sealing performance; Otherwise, the heat sealing temperature and pressure of the leaking area should be adjusted in a timely manner. Vertical bags containing liquids should be treated with greater caution. Squeezing and dropping methods can be used to detect any leakage, such as filling the bag with a certain amount of water, sealing the mouth, and testing according to the GB/T1005-1998 pressure test method. The drop test method can also refer to the above standards.
Uneven bag shape
Flatness is one of the indicators for measuring the appearance quality of packaging bags. In addition to material factors, the flatness of upright bags is also related to factors such as heat sealing temperature, heat sealing pressure, heat sealing time, and cooling effect. Excessive heat sealing temperature, pressure, and time can cause shrinkage and deformation of the composite film. Insufficient cooling can cause insufficient shaping after heat sealing, which cannot eliminate internal stress and cause wrinkles in the bag. Therefore, process parameters should be adjusted to ensure the normal operation of the cooling water circulation system.
Poor symmetry
Symmetry not only affects the appearance of stand up pouch, but also affects their sealing performance. The most common asymmetry of stand up pouch is often reflected in the bottom material. Due to improper control of the bottom material tension, it can cause deformation of the bottom circular hole or wrinkles due to mismatch with the main material tension, resulting in a decrease in heat sealing strength. When the circular hole of the bottom material deforms, it is necessary to appropriately reduce the discharge tension and increase the waiting time for correction during heat sealing to ensure that the intersection of the four layers at the bottom of the bag is fully heated. In addition, bag shape asymmetry is also related to factors such as photoelectric tracking, feeding, cursor design, rubber roller balance, and synchronization of stepper or servo motors. This issue needs to be addressed during specific operations based on different products and bag making equipment.
The emergence of shaped bag and stand up pouch has brought new economic growth highlights to the flexible packaging industry. Due to their endless business opportunities, many flexible packaging companies are currently introducing corresponding equipment and production technology in order to promote rapid development of the enterprise.
If you have any stand up pouch requirements, you can contact us. As a flexible packaging manufacturer for over 20 years, we will provide your right packaging solutions according to your product needs and budget.
Post time: Oct-21-2023
