Heat sealing temperature, heat sealing time, and heat sealing pressure are the three elements of heat sealing bag making.
1. Heat-sealing pressure The function of heat-sealing pressure is to make the polymer resin film in viscous flow state effectively penetrate and diffuse between the heat-sealing interfaces, so as to achieve a certain heat-sealing effect. To achieve the desired heat seal strength, appropriate pressure must be applied. For general thin and light medical packaging bags, the heat sealing pressure must be at least 20 N/cm2, and as the total thickness of the composite film increases or the width of the heat seal increases, the required pressure should also increase accordingly. If the heat sealing pressure is insufficient, it is difficult to achieve true bonding and mutual fusion between the two layers of plastic film heat sealing materials, resulting in partial heat sealing, or it is difficult to eliminate the air in the heat sealing layer, causing virtual sealing or unevenness. However, when the heat sealing pressure is too high, the molten material will be squeezed out, and part of the heat sealing material is squeezed away, causing the weld edge to form a semi-cut state, and the weld is brittle, affecting the heat sealing effect and reducing the heat seal. strength. Generally, after heat sealing, the strength loss of the sealing part shall not be greater than 10% to 15%. Changes in pressure can change the heat sealing characteristics. Obviously, the greater the pressure, the required heat sealing time or heat sealing temperature can be reduced, but at the same time the heat sealing range will become narrower. In actual operation, the pressure can be adjusted. A higher operating temperature is adopted to increase the output by shortening the heat sealing time. However, it is difficult to control the operation and special care must be taken to avoid negative effects.
2. Heat sealing temperature The function of heat sealing temperature is to make the adhesive film layer heated to a r
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