1. Primary and auxiliary materials' primary aluminum foil is the carrier of the adhesive layer, its quality has a great impact on the product's heat sealing strength. On the one hand is the surface of the original aluminum foil oil, which will weaken the adhesive and the original aluminum foil between the adhesive relay. If the surface of the original aluminum foil is greasy and the surface tension is less than 31×10-3 m, it is difficult to achieve the ideal heat sealing strength. On the other hand, the metal composition and surface luminosity of the original aluminum foil is not enough to affect the strength of the heat seal, we must strictly control the quality of the original aluminum foil.
2. The adhesive is a special material containing solvents, it is a certain process condition, coated in the original aluminum foil dark side (or light side), after drying the formation of the adhesive layer, the heat sealing strength of the product plays a decisive role. At present, most domestic manufacturers use imported raw materials to prepare adhesive, the product can achieve a higher heat sealing strength. But the price of imported raw materials is too expensive, in order to get the high profits of the products, some strong scientific research forces of the manufacturers began to research and develop similar domestic raw materials.
3. the production process under a certain process parameters control, so that the adhesive on the surface of the original aluminum foil coated into a film, film quality will directly affect the product's heat sealing strength. The more important parameters include coating speed, drying temperature, coating roller shape, depth, number of lines and scraper position, Angle. The speed of the coating determines the drying time of the coating in the drying channel. If the coating speed is too fast, drying temperature is too high, will make the coating surface solvent volatilization too fast, resulting in the residual of the solvent in the film, film drying is not enough, it is difficult to form a dry and solid adhesive layer, this will affect the thermal sealing strength of the product, the product layer between layer adhesion. The roller shape, depth, number of lines and scraper position, Angle determines the thickness and uniformity of the coating film. If the selection or adjustment is not appropriate, the adhesive can not be evenly coated on the surface of the original aluminum foil resulting in uneven film formation, the product will not be a good thermal sealing effect, strength will also be affected.
4. Heat seal temperature is an important factor that affects the strength of the heat seal. The temperature is too low to heat seal the adhesive layer with PVC film, and the bonding between the adhesive layer and PVC film is not firm. If the temperature is too high, the seal will be affected. Therefore, a reasonable heat seal temperature is usually between 160℃ and 180℃.
5. To achieve the ideal heat sealing strength, it is necessary to set a certain heat sealing pressure. If the pressure is insufficient, not only can not make the adhesive layer of the product and PVC film fully fit the heat seal, or even make the bubble between the two, not to achieve a good heat seal effect. Therefore, the national standard stipulates that the pressure of heat sealing is 0.2×10Pa.
6. Thermal sealing time also affects the thermal sealing strength of the product. Under normal circumstances, under the same heat sealing temperature and pressure, a longer heat sealing time can make the heat sealing part sealing more solid and perfect, can better achieve the expected heat sealing strength. If the heat sealing time is too short, the adhesive layer and PVC film between the heat sealing is insufficient. For this reason, the national standard stipulated the scientific heat seal time is 1s.
