When printing on the gravure printing machine, the full plate of the plate cylinder is inked, and the ink of the blank part of the plate is scraped off by the squeegee to leave the ink of the graphic part, and then the paper is pressed, and the embossing roller is embossed on the back side of the paper. The ink of the concave portion is directly transferred to the paper surface, and finally the printed matter is piled up or rewinded through the delivery portion.
The main reason for the fog printing machine gravure printing machine is that the ink dissolving power is reduced, the resin and the pigment in the ink are not well dissolved together, and after dispersing, the resin adsorbs on the plate roller to form a layer of oil, which looks like a fog. .
Solution to the fog problem caused by the ink itself in the gravure printing machine:
1. Try to design a suitable resin ratio according to the different characteristics of the raw materials. The difference in the raw materials is very large. Even if the same pigments are treated differently, the nature of the pigments varies greatly. This requires the formulator of the composite ink to design the composite ink. Full of this difference. Since the inks of various colors have different requirements in the printing process, when designing the formula, the proportion of various synthetic resins in the ink formulation is designed according to the characteristics of the pigment, that is, the oil absorption amount, the coloring power, the dispersion property, and the like. This can be determined by experimentation.
In general, severe fog problems can often be solved by improving the fluidity of the ink, which is due to improved ink flow, that is, low viscosity printing. Reduce the impact of the ink on the scraper so that the scraper can clean the blank portion of the ink very cleanly.
2. Scientific application of body pigments. Adding body pigments (such as ymt ultrafine powder, ymt ultrafine barium sulfate, cc-65 powder, fh-95 powder, etc.) to the formula is not only a question of reducing the cost of the test, but after adding the body pigment, it is filled in The resin encapsulating the pigment further enhances the body of the ink, reduces the viscosity of the ink at the same printing viscosity, and improves the squeegee performance of the blade.
3, the most current use of wax powder and ok-412 matte powder to solve the fog problem. Wax powder and matte powder ok-412 is an effective auxiliaries for reducing fog problems. The particles are easily released on the surface of the ink, which enhances the squeegee performance of the blade. However, many manufacturers add wax powder and ok-412 matte powder methods, which often do not solve the problem of fog problem. It is recommended to make wax powder and ok-412 matte powder into semi-finished products, and the fineness of ink grinding is qualified. After that, it is added at a high speed and the polishing is not performed, which reduces the effect of solving the fog problem.
4. Use a gravure printing machine to increase the compatibility of the pigment and synthetic resin with a suitable wet dispersing aid. The purpose of adding a wetting and dispersing aid to the formulation is to solve the problems of the formulation system, including poor pigment dispersion, poor coating of the pigment by various synthetic resins, and poor stability of the system itself, and these problems are solved. If it is not good, it will often bring the problem of fog. It is recommended to use l-18 dispersant and gk-208 additive to disperse black, blue and red pigments.
5, the use of additives to solve the problem of fog. According to the foreign experience in solving the problem of fog in high-speed printing, it is recommended to use ak-505 additive, which is to reduce the affinity of the composite ink and the chrome layer. It is not easy to adhere to the printing plate. At present, many gravure printing machine manufacturers in China have a good application effect.
6. Design the formula with a new resin system. As mentioned above, the cl-pp type composite ink is more prone to fog problem, and it is recommended to use the bk-6380 resin system instead of the cl-pp system.
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