The problems that often occur in the process of offset printing of cigarette packaging metal inks and corresponding solutions mainly include the following aspects.
(1) Metallic pigments cannot be printed. This is due to the long ink path of the offset printing press. During high-speed printing, the colloidal rollers frictionally generate heat, while the metallic pigments have coarse particles and good thermal conductivity, which increases the discrete force between the metallic pigment and the binder. Metal pigments do not transfer. The usual solutions are: reduce the speed, increase the viscosity of the ink, and use alcohol wetting fluid to reduce the temperature of the roller.
(2) The brightness of the printed gold (silver) is not enough, and it can be printed twice, and after the gold (silver) ink is printed, a layer of varnish is applied.
(3) When printing gold (silver) ink, the background color is degraded. This is because the viscosity of gold and silver ink is relatively low. This problem can be solved by increasing the viscosity of gold and silver ink.
(4) There is a phenomenon of falling gold. When gold and silver ink is printed on paper with strong absorption (such as offset paper), the link material penetrates into the paper too much, which may cause falling gold and insufficient gloss. The general solution is : Adding a part of yellow ink to gold ink, or laying a yellow net under the gold plate to increase the adhesion of gold ink; In addition, you can also add red dry oil to dry the gold ink from outside to inside, first on the ink surface. Form a protective film.
(5) The metal ink layer cannot be stamped with anodized aluminum. Since the gold powder particles are relatively thick, if the anodized aluminum is stamped on the gold ink, hot stamping may not occur. The general solution is to select an appropriate type of anodized aluminum or Unload the gold version of this stamping location.
(6) Stearic acid in the ink is replaced, usually due to the low pH of the wetting fluid. In order to prevent stearic acid from being replaced, the pH of the wetting fluid should not be too low and should generally be controlled at about 5.5.
Reprinted from: China Cigarette Ink Information Network
