Common printing faults and treatment methods of gravure ink

1. A53 type A54 type ink has poor reproducibility

Reasons: First, the viscosity of the ink is too low, resulting in poor transfer of dark tone parts, and even the contrast of the layer has a tendency to weaken. The second is the excessive penetration of ink due to uneven plastic clothing or rough paper, and the third is the poor reproducibility of the printed ink film due to the poor coloring power of the ink gel or the pigment in the ink system.

Treatment methods: First, the proportion of pigments in the ink system is suitably large or choose pigments with high coloring power as the coloring agent; second, the printed (textured) meshes are shallower when making plates. The third is to increase the proportion of wetting and dispersing agent to improve its color development. The fourth is to properly add antifreeze organic solvents such as propylene glycol butyl ether, etc., to avoid gel and maintain the fluidity of the ink. Fifth, it is appropriate to add non-surfactants such as stearic acid to prevent the ink from glossing, especially the transfer performance, due to penetration after printing.

2. Fog and paste on the ink film

Reasons: First, the water-type gravure (A53, A54) ink is printed at high speed (150 ~ 300mmin), which causes fog or paste. This is often due to the slow drying of the ink, especially the formula design of the water-based binder and the medium of water or alcohol, ester organic solvent in the ink system is unreasonable, resulting in the matt or fogging of the ink film surface after printing shape. Second, due to the poor solubility of thinner and ink, poor solubility after addition, there are also dry ink on the plate that increases the resistance of the blade or paper powder on the substrate, and plastic powder is mixed into the paste plate.

Treatment methods: one is to improve the accuracy (macro) and surface finish of the plate; the other is to increase the pressure of the blade; the third is to adjust the solubility of the thinner and ink.

3. The ink dries slowly

Reasons: First, the slow drying of the ink is often caused by the slow evaporation rate of water. It is usually caused by the high viscosity or the depth of the plate hole and the ink film is too thick or because the non-absorbent plastics, aluminum foil, etc. do not absorb the ink. It is caused by the condition of completely no wind or no drying equipment (including facilities) or low temperature of drying (including infrared magnetic wave drying power is small) and so on.

Treatment method: First, it is to improve the ordinary heat blowing method, the temperature of the hot roller type is 20 to 30 ℃ higher than that of the solvent type; second, the frequency of the electromagnetic wave from the previous high-frequency dielectric heating 10 to 150MHz is changed to 300 to 3000MHz Microwave heating and drying; three is to use preheating to increase the surface temperature of paper or plastic or aluminum foil for packaging and printing; four is to increase the ambient temperature (especially the printing plate).

4. Poor adhesion fastness

Reasons: First, the substrate is not processed well; second, the wrong ink is used; third, the ink system contains excessive surfactant; fourth, the printing pressure is too small; fifth, the viscosity of the ink is unsuitable; sixth, the ink film has excessive moisture or Solvent.

Processing methods: one is to reprocess the substrate; the second is to replace the appropriate ink; the third is to choose inks that do not contain surface activity; the fourth is to increase the printing pressure; the fifth is to select inks with high resin content and low viscosity; the sixth is In the ink system or the design of the thinner formula, the gradient mixed solvent is used as much as possible or the printed product is cut and placed in the drying room to eliminate excess water.

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