SICHUAN UNIWELL BIOTECHNOLOGY CO.,LTD. , https://www.uniwellbio.com
(1) The surface tension of the ink is low, resulting in poor coating effect of the adhesive and uneven coating, so the adhesion between the ink layer and the aluminized layer and the tightness between the layers will be different, thereby plating The reflective effect on the surface of the aluminum layer is also strong and weak, forming a white or gray spot on the visual.
(2) The hiding power of the ink is not strong or the leveling property is poor, resulting in uneven covering (especially white ink and light yellow ink). In places where the hiding effect is not good, the color of the aluminized layer will permeate through the ink.
(3) The adhesive concentration is too high, the viscosity is too large, and the ink is easily adhered to the glue to change the color of the printed layer. 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 causes spots.
(4) The ink and the adhesive do not match, so that the adhesive has poor penetrability to the ink, and there is a phenomenon of repulsion and speckle.
(5) The composite film is not completely dried, and the solvent volatilization is insufficient, causing too much residual solvent in the adhesive, and some of the ink layer is dissolved and glazed to form spots, and when it is mature, many tiny bubbles are formed.
(6) The aluminized film itself has poor quality and has many light-transmissive points. After the composite, the reflectivity of the aluminized layer is different, forming spots.
(7) The temperature of the drying tunnel (especially the first drying tunnel) is too high, causing the surface glue to dry too fast, and the surface is conjunctiva; when the internal solvent is vaporized in the second and third drying tunnels, it will break through the surface glue. The film, which squeezes the adhesive, exposes the ink, causing uneven thickness of the adhesive layer, thereby generating spots.
(Source: Anhui Printing Network)
Technical Analysis: Analysis of the Causes of Speckles Produced by Composite Membranes
White or gray spots sometimes appear on the surface of the composite film. This is easy to occur during the production of full-size inks and composites with aluminized films. The main reasons are as follows.