Metallized film often occurs in composites. The composite film has obvious white or gray spots. The distribution of spots is random and the size is irregular. The spots often appear in the printing of full white or light yellow background. Spots will improve after ripening.
Causes of spots
1. The hiding power of white ink and yellow ink is poor. The printing layer ink is infiltrated by ethyl acetate in the adhesive, and some of it is dissolved, especially white ink. The color material is TiO2 particles, and its particle size is larger, and There is a weak link between the binders, which is more easily infiltrated by ethyl acetate. On the one hand, it causes difficulty in drying. On the other hand, the results of different infiltration results are different in depth and cause spots.
2, the adhesion of the aluminized film itself is not uniform, the adhesion of the ink and the adhesive on the surface is different, the adhesion between the ink and the coating is low, the difference between the layers is formed, and the density is high without spots. The coating has been obviously transferred, and the reflection is formed by the reflection of the aluminum plating layer.
3, the adhesive is also an important factor, when the surface tension of the adhesive is high, the effect of infiltration and spreading on the aluminized film is poor, the adhesive coating state is not good, some adhesives with high initial adhesion, poor solvent release, high residual solvent, Spots are generated when the ink layer is wetted by residual solvent.
Measures to reduce speckle
1. Improve the thickness of the ink layer on printing and improve the hiding power.
2. In the aspect of adhesive, the special aluminum-plated composite adhesive is used, and the flattening property of the aluminum-plated adhesive is good, and the solvent release property is good.
3. When adding glue, increase the amount of curing and increase the amount of glue.
4. In the composite process, it is necessary to strictly control the composite speed and increase the exhaust air volume, which can achieve good results.
5. Also pay attention to the maintenance of the equipment, and thoroughly clean the rubber roller, flattening roller, scraper, etc.