White or gray spots may sometimes appear on the surface of the composite film. This situation is likely to occur during the production of live parts printed with full-page ink and compounded with an aluminum film. The main reasons are the following.
(1) The surface tension of the ink is low, which results in poor coating effect and uneven sizing of the adhesive. Therefore, the adhesion between the ink layer and the aluminum layer and the tightness between the layers will be different, so the plating The reflective effect on the surface of the aluminum layer is also strong and weak, forming white or gray spots visually.
(2) The hiding power of the ink is not strong or the leveling is poor, resulting in uneven coverage (especially white ink and light yellow ink). In areas where the covering effect is not good, the color of the aluminum layer will penetrate through the ink.
(3) The concentration of the adhesive is too high, the viscosity is too large, it is easy to reverse the ink into the glue, so that the color of the printed layer changes. At the same time, if the viscosity of the adhesive is too large, the fluidity is not good, and it is easy to cause uneven coating, which affects the reflective performance of the surface of the aluminized layer and produces spots.
(4) The mismatch between the ink and the adhesive makes the adhesive's permeability to the ink not good, repelling occurs, and spots will also occur.
(5) Insufficient drying of the composite film, insufficient solvent evaporation, resulting in too much residual solvent in the adhesive, part of the ink layer is dissolved and polished, thereby forming spots, and in serious cases, many tiny bubbles will form after aging.
(6) The quality of the aluminized film itself is poor, and there are more light-transmitting spots. After the compounding, the reflectance of the aluminized layer is different, forming spots.
(7) The temperature of the drying tunnel (especially the first-level drying tunnel) is too high, which causes the surface glue to dry too quickly and the surface is condensed; when the internal solvent vaporizes in the second and third drying tunnels, it will break the surface glue The film squeezes the adhesive, exposing the ink, causing uneven thickness of the adhesive layer, resulting in spots.
Bar Stool,Adjustable Bar Stools,Modern Counter Stools,Tall Bar Stools
Feat Top International(China) CO.,LTD , https://www.ft-project.com