What Are The Causes Of Bubbles in Food Packaging Bags?

1. Bubbles are generated after compounding
① If the film has poor wetting, the glue concentration and coating amount should be increased. The surface is not easily wetted and bubbles are easily generated, especially in winter. Air bubbles on the ink can be removed by increasing the amount of glue.
② If the ink surface is uneven and blistered, the laminating temperature and laminating pressure of the composite film should be increased.
③ The amount of glue coating on the ink surface is small. The laminating time of the laminating roller should be increased, a smooth roller should be used, the film should be fully preheated, the laminating speed should be reduced, the glue with good wettability should be selected, and the ink should be selected correctly.
④ The additives (lubricant, antistatic agent) in the film are penetrated by the glue. Do not use films with a storage period of more than 3 months because the corona treatment has been lost.
⑤ In winter, when the temperature is low, the adhesive transfers to the film and ink, causing poor wetting and adhesion. The operating place must be kept at a certain temperature.
⑥ If the drying temperature is too high, the glue will bubble or the skin will be crusted, and the inside will not be dry. The glue drying temperature should be adjusted.
⑦ If air is entrained between the films of the laminating roller, the temperature of the laminating roller should be increased and the laminating angle should be reduced (bubbles are likely to be generated when the film is thick and hard).
2. There are no bubbles after compounding, but bubbles are produced after aging.
① Due to the high barrier properties of the film, the CO2 gas generated when the glue is cured remains in the composite film, and there are bubbles in unprinted areas. The curing dose should be increased to allow the glue to solidify during drying.
② The ethyl acetate in the glue is a good solvent for the ink binder. The glue dissolves into the ink, leaving only bubbles on the ink. This prevents moisture from penetrating into the glue and increases the drying temperature of the glue, reducing the penetration of the ink.