Eight issues that inks need to pay attention to in the printing process

Question 1: How does the ink's characteristics determine the amount of fountain solution?

The size of the ink flow can affect the amount of fountain solution used during printing. One of the reasons for using the fountain solution in the printing process is to make it easier for the water to form a water film on the non-printed portion, and it is not easy for the ink to spread to these portions. Assuming that the ink has a small fluidity, it will spread slowly on the printing plate, and the ink will stay shorter in the non-printing part. In this case, we can use a smaller amount of fountain solution; on the contrary, assuming that the ink is highly mobile, we must appropriately increase the amount of fountain solution to prevent the ink from sticking on the non-printed part.

Question 2: What happens to the ink after emulsification?

If the ink is emulsified, it will produce the following changes: (1) After emulsification. The water is shot into the ink, occupying the space between its original molecules, thus increasing the volume of the ink; (2) also because the water occupies the space of the ink, so that the pigment particles on the ink surface occupy The proportion of the area is reduced. Since the pigment reflects the color light in the air, we can see the color of the ink, so the pigment particles are less, the ink can reflect less light, and destroy the hue of the ink. Brightness and saturation; (3) Water penetrates the ink and his viscosity drops.

Question 3: What is the problem with emulsified ink printing?

In fact, once the ink is emulsified, its hue. Brightness and saturation can be damaged by the infiltration of water molecules, so printing with these inks will certainly have a problem of hue shift. Since the saturation of the ink is lowered, the amount of ink has to be increased during printing, and thus another problem of an increase in the value of the density in the field is brought about.

Question 4: What is the role of ink viscosity in printing?

Viscosity can also be called internal friction or cohesion. From a physics perspective, its direction of force is exactly the opposite of the flow of liquid, and it is a resistance to flow. As explained by ink transfer, the viscosity is generated based on the fact that during the transfer process, the ink layer of the ink is pulled apart, and in order to counteract this pulling force, another inward force appears, which is viscosity. Offset printing often requires the ink to have a certain viscosity, so that when the ink spreads on the plane, there is a certain degree of adhesion, making the dots clear; on the other hand, it can make the surface speed of the ink roller equal, helping the ink to be uniformly transferred and maintained The thickness of the ink layer.

Question 5: What is the problem if the viscosity is too large or too small?

If the viscosity is too large, the ink is easily non-uniform, the paper and paper dust are easily peeled off, and the paper is difficult to be peeled off from the rubber roller, and the printing quality is greatly affected; while the viscosity is large, the ink will spread slowly on the printing plate. The ink layer on the plate, after several rotations, the remaining ink layer is not enough to protect the layout, the result will not withstand the pressure of printing and the role of the fountain solution, making the plate easy to pattern. However, if the viscosity is too small, the ink will be too emulsifiable and dirty, which will result in poor printing quality.

Question 6: What is the role of ink fluidity?

The relationship between fluidity and viscosity is inversely proportional, the greater the fluidity, the lower the viscosity; the lower the fluidity, the higher the viscosity. The fluidity of the ink is good, and the quality of the printing can be guaranteed to a certain extent, because under the same pressure, the ink can be spread on the surface of the ink roller, and the ink film with uniform thickness can be easily spread, and the ink can be transferred well, so that the printing will not happen. There are uneven prints.

Question 7: How many types of drying ink?

In fact, different inks use different methods according to their characteristics and different printing methods to dry the ink. Generally speaking, the following are not available: (1) Oxidation of ink. This dry form of polymeric conjunctiva is the main dry form of offset printing; (2) Permeation drying. When the ink is printed on paper, its binder material penetrates into the interior of the paper due to the capillary action of the paper fibers, and (3) it is dried. After the ink is printed on the paper, only part of it will seep through the paper, but most of it will be lost.

Question 8: Why do we need driers in ink?

When the drying ability of the ink's binder material is not enough to meet the time requirement of the printing process, we must add a driers to the ink to speed up the drying process. The driers can be combined with the anti-oxidation substances in the ink to eliminate them and reduce the adverse effects of the anti-oxidation substances. In addition, the driers can directly absorb the oxygen in the air, making it easier for the ink to obtain the oxygen needed for drying, and accelerate the oxidative drying.