How to control the ink printing viscosity
2024-02-27 10:09:54
In plastic printing, the control of ink printing viscosity is the key. Especially in the high-speed rotary gravure printing, whether the ink printing viscosity is controlled properly is directly related to the vast majority of quality issues such as the transfer of pigments, dirty prints, inky glossiness, firmness of pigments, and static electricity, affecting printing. Crystal yield and work efficiency. How to control the ink printing viscosity, in order to take into account in many ways, to ensure the quality of the printing product? This requires us to understand the relationship between ink printing viscosity and the quality issues.
We know that inks are made up of organic solvents, detergents, pigments, additives, additives, etc. When these raw materials have been determined, the degree of processing, methods, and composition of the ingredients have been determined. The quality of the pigment transfer is mainly related to the printing viscosity of the ink. Practice has proved that the ink printing viscosity in a certain range (11-24 seconds, using the Zahn viscosity cup No. 3), the greater the ink printing viscosity, the effect of pigment transfer is poor. Because the role of the solvent is to dissolve the resin or additives and auxiliaries, the fluidity is imparted, so that the pigment is easily dispersed. When the ink printing viscosity is too large, the entire ink system is in an oversaturated state, and the flowability of pigments and the like is poor. Evenly dispersed, but in groups, it is easy to accumulate together, so that the pigment can not enter and exit the mesh smoothly. When the viscosity of the ink is too high, the pigment cannot even enter the mesh at all, let alone transfer. This is the so-called blockage phenomenon. Therefore, we only need to make the colloidal system consisting of resin, pigment, etc. and organic solvent not be in supersaturation. It is between saturation and non-saturation, so that pigments and other substances can be well dispersed in them to form a uniform and delicate colloidal system. In this way, the paint can go in and out of the mesh smoothly, and the problem can be solved. Some ink manufacturers recommend that the ink be printed between 15-18 seconds (3 on the Zahn viscosity cup). However, in practice, especially in high-speed gravure printing machines (print speeds of 100 to 260m/min), in order to ensure the transfer of good results, but can print for a long time, improve efficiency, ink printing viscosity is generally 11-15 seconds (Zarne Viscosity Cup No. 3) Find the ideal point between them.
In plastic gravure, dirty print problems often occur. The phenomenon is that the non-printing surface of the roller is also stained with a layer of resin (entrained with pigment in the resin) and transferred to the substrate to make the substrate stain-like, or appear as a linear stain. The root cause of the dirty plate phenomenon is related to the printing viscosity of the ink, in addition to the hardness of the blade, the pressure of the blade, the contact angle of the blade, and the quality of the plate cylinder. As mentioned above, when the printing viscosity is too high, the resin pigments and other substances have poor fluidity and cannot be evenly dispersed, and are likely to be stacked together. Under the relatively high-speed movement of the doctor blade and the plate cylinder, the doctor blade and the plate cylinder are easily damaged, and thus are easy to damage. Shallow fouling occurs, and since the resin etc. is also in a supersaturated state, a large amount of resin is agglomerated together, and the resin has an affinity for the roller. Under the pressure of the doctor blade, the resin tightly adheres to the drum (in the resin Entrained with pigment). In this way, there will be flaky dirt, and - generally speaking, the smaller the printing viscosity of the ink, the less likely it is that graffiti will occur.
If the ink printing viscosity is too small, indicating that the ink contains many organic solvents, and resin, pigment and other components are relatively small, so you can not form a smooth film when drying, because the white, become dull, lack of luster . Therefore, if the ink needs to have a good gloss, generally consider using a larger ink to print the viscosity (13 to 19 seconds, the Zahn No. 3 cup), that is, the resin and pigment ingredients are relatively more to meet the Indian Need for goods.
At the same time, when the ink is printed on the plastic and dried into an ink film, the coated pigment can be firmly attached to the plastic surface, and the resin is the main material for the plastic to be firmly attached. Therefore, the color fastness of the pigment is also related to the printing viscosity of the ink. This shows that the proportion of the resin and the pigment in the ink should not be too large or too small, but should be within the normal range, and the bonding strength of the pigment is large.
Under the normal environmental humidity, the printing viscosity of the ink is more than 16 seconds (3 cups of Zahn) and the electrostatic phenomenon will not occur. The printing viscosity of the ink is less than 16 seconds (Zahn 3 cup). As the viscosity becomes smaller, the electrostatic phenomenon such as beard-like, streak-like, edge-repulsion, flying ink, poor transfer, and irregularly-formed water stains will follow. Occur and increase.
Therefore, based on the above reasons, we generally look for the ideal state of the ink's printing viscosity between 11-17 seconds (the Zahn No. 3 cup). If there is an electrostatic phenomenon within this range, in accordance with the principle of mutual consideration, we generally do not eliminate the static electricity by increasing the printing viscosity of the ink, but by maintaining the normal environmental humidity, changing the composition of the thinner composition, and installing the static brush, and use Anti-static agents and other methods to eliminate static electricity, so as to ensure quality, while improving efficiency and yield, lay the necessary foundation for the company to obtain profits.
Source: "Printing World" Author: Li Yun District
We know that inks are made up of organic solvents, detergents, pigments, additives, additives, etc. When these raw materials have been determined, the degree of processing, methods, and composition of the ingredients have been determined. The quality of the pigment transfer is mainly related to the printing viscosity of the ink. Practice has proved that the ink printing viscosity in a certain range (11-24 seconds, using the Zahn viscosity cup No. 3), the greater the ink printing viscosity, the effect of pigment transfer is poor. Because the role of the solvent is to dissolve the resin or additives and auxiliaries, the fluidity is imparted, so that the pigment is easily dispersed. When the ink printing viscosity is too large, the entire ink system is in an oversaturated state, and the flowability of pigments and the like is poor. Evenly dispersed, but in groups, it is easy to accumulate together, so that the pigment can not enter and exit the mesh smoothly. When the viscosity of the ink is too high, the pigment cannot even enter the mesh at all, let alone transfer. This is the so-called blockage phenomenon. Therefore, we only need to make the colloidal system consisting of resin, pigment, etc. and organic solvent not be in supersaturation. It is between saturation and non-saturation, so that pigments and other substances can be well dispersed in them to form a uniform and delicate colloidal system. In this way, the paint can go in and out of the mesh smoothly, and the problem can be solved. Some ink manufacturers recommend that the ink be printed between 15-18 seconds (3 on the Zahn viscosity cup). However, in practice, especially in high-speed gravure printing machines (print speeds of 100 to 260m/min), in order to ensure the transfer of good results, but can print for a long time, improve efficiency, ink printing viscosity is generally 11-15 seconds (Zarne Viscosity Cup No. 3) Find the ideal point between them.
In plastic gravure, dirty print problems often occur. The phenomenon is that the non-printing surface of the roller is also stained with a layer of resin (entrained with pigment in the resin) and transferred to the substrate to make the substrate stain-like, or appear as a linear stain. The root cause of the dirty plate phenomenon is related to the printing viscosity of the ink, in addition to the hardness of the blade, the pressure of the blade, the contact angle of the blade, and the quality of the plate cylinder. As mentioned above, when the printing viscosity is too high, the resin pigments and other substances have poor fluidity and cannot be evenly dispersed, and are likely to be stacked together. Under the relatively high-speed movement of the doctor blade and the plate cylinder, the doctor blade and the plate cylinder are easily damaged, and thus are easy to damage. Shallow fouling occurs, and since the resin etc. is also in a supersaturated state, a large amount of resin is agglomerated together, and the resin has an affinity for the roller. Under the pressure of the doctor blade, the resin tightly adheres to the drum (in the resin Entrained with pigment). In this way, there will be flaky dirt, and - generally speaking, the smaller the printing viscosity of the ink, the less likely it is that graffiti will occur.
If the ink printing viscosity is too small, indicating that the ink contains many organic solvents, and resin, pigment and other components are relatively small, so you can not form a smooth film when drying, because the white, become dull, lack of luster . Therefore, if the ink needs to have a good gloss, generally consider using a larger ink to print the viscosity (13 to 19 seconds, the Zahn No. 3 cup), that is, the resin and pigment ingredients are relatively more to meet the Indian Need for goods.
At the same time, when the ink is printed on the plastic and dried into an ink film, the coated pigment can be firmly attached to the plastic surface, and the resin is the main material for the plastic to be firmly attached. Therefore, the color fastness of the pigment is also related to the printing viscosity of the ink. This shows that the proportion of the resin and the pigment in the ink should not be too large or too small, but should be within the normal range, and the bonding strength of the pigment is large.
Under the normal environmental humidity, the printing viscosity of the ink is more than 16 seconds (3 cups of Zahn) and the electrostatic phenomenon will not occur. The printing viscosity of the ink is less than 16 seconds (Zahn 3 cup). As the viscosity becomes smaller, the electrostatic phenomenon such as beard-like, streak-like, edge-repulsion, flying ink, poor transfer, and irregularly-formed water stains will follow. Occur and increase.
Therefore, based on the above reasons, we generally look for the ideal state of the ink's printing viscosity between 11-17 seconds (the Zahn No. 3 cup). If there is an electrostatic phenomenon within this range, in accordance with the principle of mutual consideration, we generally do not eliminate the static electricity by increasing the printing viscosity of the ink, but by maintaining the normal environmental humidity, changing the composition of the thinner composition, and installing the static brush, and use Anti-static agents and other methods to eliminate static electricity, so as to ensure quality, while improving efficiency and yield, lay the necessary foundation for the company to obtain profits.
Source: "Printing World" Author: Li Yun District
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