The Influencing Factors of Ink Flying and Its Elimination Methods

The phenomenon of flying ink appears, that is, polluting the environment and harming the health of the operators. The following is a brief analysis of this issue.

1. Reasons for flying ink

When the ink is transferred, the fibers are cut at two or more places at the ink rollers that are in contact with each other. When the fibers are cut or elongated, the pieces are broken, and the surface tension becomes spherical. At this point, the electric double layer existing at the interface between the fiber material and the broken piece is destroyed, and part of it remains in the ink, and the other part escapes to the atmosphere with the opposite charge. When the fiber is shortened, the residual charge in the ink is gradually accumulated on the ink roller and the surface of the paper. Due to the same charge as the ink, the fragments are repelled in the air to form a flying ink when they are close to the ink roller or paper.

When a high-speed machine uses a highly viscous ink and a low-quality linking material, the ink tends to rotate during the rotation of the ink roller to cause serious ink flying. Therefore, different types of printing machines need to select the corresponding ink to match.

2. Factors affecting flying ink

(1) Ink viscosity is too large, the ink is stretched at the ink roller outlet, and it is easy to produce flying ink. At the same time, it also causes uneven ink transfer, which causes the paper to be fluffed and de-powdered, making it difficult to strip the paper from the blanket. Easy to print , Off-type, etc.; viscosity is too small, the ink layer is not good, easy to produce flying ink, easy to make the ink emulsification, from the dirty, paste version, network expansion, affecting the quality of printed products.

(2) The thicker the ink layer on the ink roller, the greater the flying ink. Proofing on coated paper, when the thickness of the ink layer is 1.2μm, the ink on the plate can reach 2.8g/m2; but with offset paper printing, the ink on the printing plate must reach 4g/ m2 at least. When the paper performance is not good on the adhesion of the ink, it is easy to cause the ink roller to pile up ink and thus generate ink.

(3) When the surface of the ink roller is uneven and cracks on the surface are dry, some of the ink layers are thickened and the amount of ink mist is increased.

(4) The printing speed increases and the flying ink increases.

(5) The relative humidity of the air is small, which promotes the generation of flying ink. When the humidity increases, the charge decreases and the amount of flying ink decreases.

(6) If there are too many fountain solutions in the ink, a severe W/O emulsified ink is formed, the viscosity drops sharply, and the ink becomes shorter, resulting in a serious flying ink phenomenon. At the same time, the fountain solution immersed in the ink will also corrode the metal ink roller, forming a hydrophilic layer on the surface of the ink roller and repelling the ink, resulting in deinking of the metal ink roller.

(7) The binder of the high molecular weight ink easily pulls filaments when the ink is split, resulting in flying ink.

3. How to eliminate flying ink

(1) Select high-quality alcohol-resistant inks to suit high-speed printing.

(2) Remove the rubber roller periodically and thoroughly clean it, so that the ink layer is even and the ink transfer performance is improved.

(3) The alcohol concentration is controlled between 10% and 15%. It is not suitable for too low or too high.

(4) The amount of fountain solution should not be too large, otherwise it will cause the ink to become shorter and unfavorable for printing.

(5) When the electrolyte is added to the ink, the flying ink will be reduced. With the addition of the electrolyte, the electrical conductivity will increase, and the flying ink will disappear completely.

In short, the phenomenon of flying ink may occur at any time during the printing process due to the contact rotation of the two rollers. This requires the operator to not only have a high-skilled operation level, but also be familiar with the data and specifications involved in the printing and generate the ink as much as possible. The probability is minimized.

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