1. Small ink spots

Small ink spots are less likely to occur immediately after general film coating, unless they are residues, impurities, etc.

This phenomenon may occur in the aluminium coating for a period of time after coating because of the corrosion of the ink to aluminium, which may occur when the ink presents certain acidity or alkalinity and the amount of glue on it is too small to form a continuous layer.

2. Small grey points (i.e. small solid points)

There are two possibilities for the occurrence of small gray spots. One is that the non-uniform rollers cause rubber spots, and the other is that the ink caused by the non-uniform ink does not have compaction spots.

Both possibilities are related to the process. Packaging bag manufacturers can adjust the process, that is, to increase the thickness of the glue.

3. Small white dots

Generally, the discoloration of ink on the surface is easy to occur, and most of them occur in the composite of aluminized film.

There are two reasons for the appearance of small white spots: one is that the covering power of ink is not strong or uneven, especially white ink, which makes the color of aluminium permeate out, and there is no infiltration of aluminium color into small white spots; the other is that the drying temperature (especially the first drying channel) is too high or the amount of glue is too thick, which results in the first drying channel. When the surface of the inner glue layer coagulates and the ethyl ester rushes out in the second and third drying channels, the glue is extruded to show the ink color.

The solution is to increase the covering power of ink or adjust the suitable temperature of the first, second and third drying paths to gradually raise the temperature so as to avoid the excessive temperature of the first stage.

4. Small Crystal Points

There are many small crystalline points on the transparent film, there are two kinds of concave and convex, the causes are different: the protruding small crystalline points are mostly due to collagen, if not in accordance with the correct order (first add diluent, then curing agent) first reinforcement agent, then diluent, generally more than a dozen hours later there will be small crystalline points, there are also other. Maybe it's because the machine has been used for a long time, but it hasn't been cleaned.

The method of eliminating microcrystalline point is to mix glue strictly according to the correct method of mixing glue, the machine must be cleaned after use; the concave microcrystalline point, carefully observed with a magnifying glass, will find that there are small bubbles, which is mainly caused by excessive moisture, we should pay attention to the water content of the diluent must not exceed.

5. Small Scar Points

Small scar points refer to the points larger than the above small points, convex and concave around, mainly due to the uneven treatment of membrane activation, the same scar points appear in the printing process, or may be caused by too long activation time.

6. Waves

Wave lines are easy to occur on the white film, mainly because the molecular weight of rubber is not uniform. After the hot drying channel and the hot roller, the elastic polymer chain shrinks, and the molecular shrinkage of different molecular weights is inconsistent. This inhomogeneous internal shrinkage causes wave lines. The reason for this should be considered.

7. Effect of Thin Film on Surface Quality

Similar phenomena of the above six phenomena may be caused by various reasons of the smoothness and uniformity of the film surface. To distinguish the reason of the film from the six cases mentioned above, the film without film can be observed carefully with a magnifying glass.