Paper Gift Bags With Flat Paper Handles Paper Gift Bags With Flat Paper Handles Paper Plate Surface Tension Demand

Paper Gift Bags With Flat Paper Handles Paper gift bags with flat paper handles Paper plate surface tension demand

From the surface tension Angle analysis, if the ink from the plate fast, do not make the ink residue on the plate, of course, to choose the plate surface tension and ink surface tension in the value of similar, so that the ink on the plate wetting Angle close to 90 degrees. But because the flexo printing process of the printing plate is the ink transfer "setter" role, first from the roller to absorb ink, and then as far as possible without residual transfer to the printing material, so the requirements of the plate and ink surface tension is absolutely equal to it is unrealistic. A reasonable choice is the surface tension of the plate is slightly greater than the surface tension of the ink, but the value needs to be as close as possible. Only in this way, the printing plate can not only maintain good inking, but also achieve good ink transfer.

When flexo printing plate blocking failure, the ink on the plate is not accumulated in the inking area, but stuck in the depression area, which clearly indicates that the surface tension of the inking area and the depression area of the printing plate should not be absolutely equal. According to the analysis of most flexo plate materials now, the plate itself has no difference between the inking area and the depression area, the polymer material of the plate is the same, if there is no interference of various washing solutions in the plate washing process, the surface tension should also be the same.

However, the test data show that the surface tension of the inking area is lower than that of the depression area in most plates. This is because: after the exposure of UVA in the main exposure process, the strength of the hardened resin is very different from that of the non-hardened resin. The non-photosensitive hardened resin is cleaned under the action of the plate washing brush, and the brush leaves obvious traces on its surface; The strength of the photosensitive hardened resin is very high, which not only resists the erosion of the washing solution, but also avoids the damage of the brush to its surface. Under a high-power magnifying glass, you can see that the ink area of the printing plate is smooth like a mirror, and the layout is smooth and clean, but the concave area that has been cleaned by the brush is obvious and slightly rough. Therefore, the surface tension of the plate depression area is 1 ~ 2mN/m higher than that of the inking area.

But the actual demand is: printing plate inking area of high surface tension and depression area of low surface tension. The surface tension of the inking area is high, the printing plate inking is good, and the amount of ink drawn from the roller is large; Depression area surface tension is low, from the dot surface overflow ink can not stick in the depression area, also can not accumulate ink on the plate, can effectively avoid blocking plate fault.

Effective use of the liquid surface tension will decrease with the rise of temperature, and the solid surface tension will increase with the strengthening of surface shear, may be an effective way to find suitable plate surface tension. In this way, it is possible to have a printing plate: the plate's depression area in the printing process presents low surface tension, so that the ink is not easy to stain on it; Inking area by printing plate and roller shear to increase the surface tension, printing plate inking performance is good. The final confirmation of the surface tension of the printing plate must be matched with the surface tension of the ink, which needs to be carefully checked and demonstrated.

In order to solve the hidden danger of flexo plate blocking from the aspect of plate quality, we need a plate with suitable surface tension and numerical stability, which is the new demand of printers for plate quality performance.

When the platemaking process can provide a plate with stable surface tension for flexo printing, the next problem is ink. Our target is inks that need to work well with plate surface tension, whether it's solvent-based inks, water-based inks, or UV inks.