Aluminum foil bag is a common material for food packaging, with good mechanical properties, long storage time, freshness and other advantages, favored by consumers. Heat sealing strength is one of the important indicators to measure the quality of aluminum foil bags, once the heat sealing strength problems, it is likely to lead to broken bags, affecting product quality. Today, starting from the factors that affect the heat sealing strength, analyze how to ensure the heat sealing strength of aluminum foil bag.
1. Raw Materials
The raw material is the carrier of the adhesive layer of the aluminum foil bag, and the material quality is not good or inappropriate, which will seriously affect the heat sealing strength. On the one hand, the surface of the original aluminum foil is greasy, which will weaken the adhesion between the adhesive and the original aluminum foil. On the other hand, the heat sealing strength is also affected by the metal composition of the original aluminum foil and the insufficient surface luminosity. The different packaging materials selected for the production of aluminum foil bags require very different heat sealing parameters in actual production, and it is necessary to adjust the heat sealing parameters reliably according to the actual production needs and product packaging performance requirements.
Two, adhesive
An adhesive is a special substance containing solvent, which is coated on the dark side of the original aluminum foil under certain technological conditions, and forms a bonding layer after drying, which plays a decisive role in the heat sealing strength of the product.
Therefore, in addition to controlling the quality of the adhesive, it is also necessary to pay attention to the coating speed and control the drying temperature. If the coating speed is too fast and the drying temperature is too high, the solvent on the surface of the coating film will evaporate too quickly, resulting in the residual solvent in the film, and the drying of the coating film is not sufficient, which will affect the heat sealing strength of the product.
Third, the cooling process
The cooling process after the hot sealing of the aluminum foil bag also needs to be careful, when the weld after the melting hot sealing is shaped with a lower temperature, it may lead to the reduction of the hot sealing strength of the aluminum foil bag because of poor cooling, and it will also affect the appearance of the smooth degree of the weld, and unqualified products appear. In general, the poor cooling of aluminum foil bags may be caused by insufficient heat sealing pressure, poor cooling water circulation, too high water temperature or not cooling in time.
Fourth, heat sealing conditions
The heat sealing temperature is an important factor affecting the heat sealing strength. If the temperature is too high, the bond between the adhesive layer and the pvc film is not strong. If the temperature is too high, the medicine will be affected. Therefore, the reasonable heat sealing temperature is generally between 150°C and 160^C.
In order to achieve the ideal heat sealing strength, it is necessary to set a certain heat sealing pressure. If the pressure is insufficient, the adhesive layer of the aluminum foil bag cannot be fully bonded with the pvc film for heat sealing, so a good heat sealing effect cannot be achieved.
The heat sealing time also affects the heat sealing strength. Under normal circumstances, under the same heat sealing temperature and pressure, a longer heat sealing time can make the heat sealing part sealed more firmly and perfect. It can better achieve the expected heat sealing strength. If the heat sealing time is too short, the heat sealing between the adhesive layer and the pvc film will be insufficient. For this reason, the national standard stipulates that the scientific heat sealing time is 1s.
Five, the product
The products that the aluminum foil bag needs to contain will also affect the heat sealing strength of the aluminum foil bag. For example, when the aluminum foil bag is used to pack small powder products, it is easy to stick to the sealing of the aluminum foil bag when it is loaded, at this time, it is necessary to adjust the packaging materials required for production and the thickness of the inner layer of the aluminum foil bag reasonably according to the packaged products, so as to ensure and improve the heat sealing strength of the aluminum foil bag.
