Heat sealing issues of composite packaging bags, fully covered

Composite Packaging Bag The type, thickness, and material quality of the heat-sealing layer material have the most direct impact on the heat-sealing strength Therefore, Shunxingyuan Packaging, a professional flexible packaging manufacturer, will summarize the heat-sealing issues of composite packaging today.

General Composite Commonly used heat-sealing materials for composite packaging bags include CEP, LPPE 、 CPP 、 OPP 、 EVA hot melt adhesive, and other ion-type resins co-extruded or co-blended modified films. The thickness of the heat-sealing layer material generally fluctuates between 20-80μm In special cases, it can also reach 100-200μm For the same heat-sealing material, the heat-sealing strength increases with the increase in heat-sealing thickness.

For example, the heat-sealing strength of retort pouches generally requires 40-50 Newtons, therefore, its heat-sealing thickness should be 60-80μm or more. The temperature control in the heat-sealing process is displayed by the temperature instrument. In the processing of heat-sealed composite bags, the more precise the temperature gauge, the better. The error range and the set value should preferably not exceed ±5℃ . The heat-sealing temperature has the most direct impact on the heat-sealing strength. The melting temperature of various materials directly determines the minimum heat-sealing temperature of the composite bag.

In actual production, due to the influence of multiple factors such as heat-sealing pressure, bag-making machine speed, and the thickness of the composite substrate, the actual heat-sealing temperature used is often higher than the melting temperature of the heat-sealing material.

The lower the heat-sealing pressure, the higher the required heat-sealing temperature. The faster the machine speed and the thicker the surface material of the composite film, the higher the required heat-sealing temperature. If the heat-sealing temperature is lower than the softening point of the heat-sealing material, the heat-sealing layer cannot be truly sealed, no matter how much the pressure is increased or the heat-sealing time is extended.

However, if the heat-sealing temperature is too high, it is easy to damage the heat-sealing material at the weld, causing melt extrusion and root cutting ” phenomenon, greatly reducing the heat-sealing strength of the seal and the impact resistance of the composite packaging bag. In the actual bag-making and heat-sealing process, the pressure of the heat-sealing tool is usually adjusted using a rotatable spring. 。

The adjustment process generally involves two springs for the tool, one on the left and one on the right. If the pressure affects the heat-sealing strength, the detection method is: Take a composite bag that is being processed. packaging bag Carefully observe the seam. If the pressure is uniform, there will be no bubbles. ;Another method is to use a long 500px wide 75px thick 5000px special smooth bamboo block for testing. Due to insufficient pressure and low strength, leakage often occurs. Therefore, uniform pressure and temperature are fundamental to reducing low strength and delamination.

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