There are sometimes white or gray spots on the surface of the composite bag that are not standardized or the product quality is not very good on the current market. What is the reason for this? YLTpacking told you today that this situation is easy to occur in the production process of full-page ink printing and compounding with aluminized film. What causes spots on food packaging bags? YLTpacking will answer the reasons for the spots on food packaging bags: (1) The surface tension of the ink is low, resulting in poor coating effect of the adhesive and uneven gluing, so the adhesion between the ink layer and the aluminized layer And the tightness between layers will be different, so the reflective effect on the surface of the aluminized layer is also strong or weak, forming white or gray spots visually. (2) The covering power of the ink is not strong or the leveling is poor, resulting in uneven covering. Where the hiding effect is not good, the color of the aluminized layer will penetrate through the ink. (3) The concentration of the adhesive is too high, the viscosity is too large, it is easy to stick the ink back into the glue, and the color of the printed layer will change. At the same time, if the viscosity of the adhesive is too large, the fluidity will be poor, which will easily cause uneven gluing, affect the reflective performance of the surface of the aluminized layer, and cause spots. (4) The mismatch between the ink and the adhesive makes the penetration of the adhesive to the ink not good, and the phenomenon of repulsion occurs, and spots will also occur. (5) The composite bag is not completely dried, and the solvent is not sufficiently volatilized, resulting in too much residual solvent in the adhesive, and part of the ink layer is dissolved and polished, thereby forming spots, and in severe cases, many tiny bubbles will be formed after curing. (6) The quality of the aluminized film itself is poor, and there are many light-transmitting points. After the composite, the reflectivity of the aluminized layer is different, thus forming spots. (7) The temperature of the drying tunnel is too high, which causes the surface glue to dry too quickly and conjunct the surface; when the internal solvent vaporizes in the secondary and tertiary drying tunnels, it will break through the adhesive film on the surface and squeeze the adhesive. Expose the ink, causing uneven thickness of the adhesive layer, resulting in spots. All in all, the above seven aspects will affect the phenomenon of speckle in the composite bag. In the production process of composite bags, skilled workers need to pay special attention to these points. For more information on composite bags, aluminum foil bags, etc., please pay attention to the professional packaging bag manufacturer – YLTpacking!
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