Offset printing Ink is an important material for offset printing. It is an essential material in the printing industry as it prints patterns, words, etc. on paper through printing, and its performance directly affects the printing quality and production efficiency of products.
Offset Printing is the technology of transferring ink to the surface of paper, textiles, plastics, leather, PVC, PC, and other materials by making plates, applying ink, and pressurizing the original manuscript of text, drawings, photos, and anti-counterfeiting, and reproducing the content of the original in bulk.
Offset Printing is the process of transferring the approved printing plate to the substrate through printing machinery and special inks.
1. How the characteristics of the ink determine the amount of fountain solution
The size of the ink flow can affect the amount of fountain solution used during printing. In the printing process, one of the reasons for using fountain solution is to make it easier for water to form a water film in the non-printing part, so that the ink does not spread easily to these parts.
Assuming that the ink mobility is small, it will spread on the printing plate slower, the ink will stay in the non-printing part of the time, it will be shorter. In this case, we can use a smaller amount of fountain solution; on the contrary, assuming that the liquidity of the ink is large, we will have to appropriately increase the amount of fountain solution to prevent the ink in the non-printing part of the adhesion.
2. What changes will be produced by ink emulsification
If the ink is emulsified, it will produce several changes as follows.
The volume of the ink increases because the water molecules run into the ink and occupy the space between its original molecules after emulsification;
Also because the water molecules occupy the space of the ink, so that the ink surface of the pigment particles occupy less area proportion. As the pigment reflects the color light in the air, we can see the color of the ink, so there are fewer pigment particles, the ink can reflect less light, and destroy the color, brightness and saturation of the ink;
Water penetrates into the ink, and its viscosity decreases.
3. What is the problem with printing with emulsified ink?
In fact, once the ink is emulsified, its hue, brightness and saturation, it will suffer damage due to the infiltration of water molecules, so the use of these inks to print will definitely have the problem of shifting hues. And because the ink saturation is reduced, the printing will have to increase the amount of ink, and thus will bring another field density value increases the problem.
4. What is the role of ink viscosity in printing
Viscosity can also be called internal friction or cohesion, from the physical point of view, the direction of its force and the flow of liquid in the opposite direction, is a resistance to flow.
Explained by the case of ink transfer, viscosity is based on the process of transfer, the ink layer is pulled apart, and in order to counteract this pull, and thus another force inward, which is viscosity.
Lithographic printing often requires a certain viscosity of the ink, in order to make the ink spread on the plane, there is a certain adhesion, so that the network clear; on the other hand, it can make the ink roller surface line speed equal, to help the ink evenly transfer and maintain a certain thickness of the ink layer.
5. What can be wrong with too much or too little viscosity?
Viscosity is too large, the ink transfer is easy to uneven, paper hair and paper powder and easy to peel off, while the paper is difficult to peel off from the rubber cylinder, the printing quality greatly affected; and viscosity, the ink on the printing plate will spread slowly, the ink layer on the printing plate, after several rotations, the remaining ink layer is not enough to protect the page, the result will not be able to withstand the pressure of printing and the role of fountain solution, so that the printing plate is easy to spend plate.
But the viscosity is too small, and will make the ink too easy to emulsify, dirty, so that the printing quality is not good.
6. What is the role of ink flow
The relationship between fluidity and viscosity is inversely proportional, the greater the fluidity, the lower the viscosity; the smaller the fluidity, the higher the viscosity.
The good fluidity of the ink can ensure the quality of printing to a certain extent, because under the same pressure, the ink can be on the surface of the ink roller, easily spread the thickness of uniform ink film, and maintain a good transfer, so that the printing will not appear uneven shades of print pattern.
7. How many kinds of ink drying methods
In fact, different inks according to their characteristics and the different ways of printing, will be used on different methods to dry the ink. Generally speaking not out of the following kinds.
Ink oxidation: This polymerization conjunctive drying form, is the main drying form of lithographic printing;
Penetration drying: When the ink printed on paper, its linking material will be due to the capillary action of the paper fiber, and penetrate the internal drying of paper;
Volatile drying: After the ink is printed on the paper, only part of it will penetrate into the paper, but most of it will be played off.
8. Why add desiccant to the ink
When the drying capacity of the ink linking material itself is not enough to match the time required for printing sets, we have to add a drying agent to the ink to speed up the drying speed.
The drying agent can combine with the antioxidant substances in the ink to eliminate and reduce the antioxidant substances' negative effects. In addition, the drying agent can directly absorb the oxygen in the air, making it easier for the ink to obtain the oxygen required for drying and accelerate the oxidation and drying.
Summary
Correct understanding and awareness of the printing of ink issues that need attention, in order to the actual production process, according to the characteristics of the printing conditions, the appropriate ink of certain properties of the corresponding adjustments and improvements to improve production efficiency and product quality will play a better role.
