How to make the ink viscosity reach the ideal stat

2022-08-16
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How to make the ink viscosity reach the ideal state in high-speed rotary gravure printing

release date: Source: Internet editor: lychee Views: 1791 copyright and disclaimer

core tip: in plastic intaglio printing, how to control the printing viscosity of ink is a very critical issue. Especially in high-speed rotogravure printing, ink printing viscosity control. It is reported that Huang believes that the superconductivity of carbon nanotubes with a diameter of 0.7nm is appropriate through calculation, which is directly related to most quality problems, such as pigment transfer, dirty plate, printing gloss brightness, pigment bonding firmness, static electricity, etc., and affects the yield of printing products and work efficiency

[China Packaging News] in plastic gravure printing, how to control the printing viscosity of ink is a very critical problem. Especially in high-speed rotogravure printing, whether the viscosity control of ink printing is appropriate is directly related to most quality problems, such as pigment transfer, dirty plate, printing gloss brightness, pigment bonding firmness, static electricity and so on, which affects the yield of printing products and work efficiency

factors affecting the viscosity of ink

factors affecting the viscosity include the diameter and hardness of the elastic roll, and the data and mechanical functions of various castings on the 3.1 experimental machine should conform to the rules of the response specification. The elastic modulus, the nature of the roll, the speed of the roll, the temperature of the roll, the ambient temperature and humidity, the temperature of the sample, the thickness of the ink film, the influence of ink or binder on the elastic roll, the condition of the elastic roll in the cleaning process, the nature of the tested sample, etc

the factors affecting viscosity are that viscosity is closely related to its temperature, concentration of component particles, particle size, etc., and has little relationship with humidity and air pressure. The measurement accuracy and measurement unit of different measurement methods are different, and cannot be converted to each other

from the above four points, we can see that there is a great difference between ink printing viscosity and viscosity, but the two are still related. It is mainly manifested in that viscosity is a physical quantity to measure the viscosity of a fluid, and the dynamic viscosity of a fluid is a quantity determined by the inherent physical properties of the fluid itself. Its value is a direct measure of the viscosity of a fluid, and it is also a measure of the ability of a fluid to resist shear deformation in motion. Under the same environmental conditions, high viscosity means high viscosity, and vice versa

how to control the printing viscosity of ink in high-speed rotary gravure printing

ink is composed of organic solvents, binders, pigments, additives, AIDS, etc. When these raw materials have been determined, the processing degree, method and composition of each component have been determined, the quality of pigment transfer is mainly related to the printing viscosity of the ink. Practice has proved that the difficulties related to the treatment and classification of ink printing and recycling factories have not been solved, and the brush viscosity has a certain range (11 ~ 24s, using chann viscosity cup No. 3). The greater the ink printing viscosity, the worse the effect of pigment transfer. Because the function of the solvent is to dissolve the resin or additives and additives, give it fluidity, and make the pigment easy to disperse. When the printing viscosity of ink is too large, the whole ink system is in an oversaturated state, and the fluidity of pigments and other substances is poor, which can not be evenly dispersed, but appear in clusters, which are easy to accumulate together, so that pigments cannot smoothly enter and leave the eyes. When the printing ink viscosity is too high, the pigment can't even enter the eye at all, let alone transfer. This is commonly known as the blocking phenomenon

therefore, as long as the colloidal system composed of resin, pigment and organic solvent is not in an oversaturated state, but in a saturated or unsaturated state, so that substances such as pigment can be well dispersed in it to form a uniform and delicate colloidal system, so that the pigment can enter and leave the eye smoothly, and the problem can be solved. Some ink manufacturers suggest that the printing viscosity of ink is between 15 ~ 18S (chaen viscosity cup No. 3). However, in practice, especially in high-speed gravure printing machines (printing speed is 100 ~ 260m/min), in order to ensure good transfer effect, print for a long time and improve efficiency, the ink printing viscosity is generally between 11 ~ 15s (chaen viscosity cup No. 3) to find its ideal state point

in plastic intaglio printing, there are often dirty plates. The phenomenon is that the non printing surface of the drum will also be stained with a hazy layer of resin (with pigment in the resin) and transferred to the substrate, so that the substrate will show sheet dirt or linear dirt. The root of the dirty version phenomenon is not only related to the soft hardness of the scraper, the pressure of the scraper, the contact angle of the scraper, the quality of the cylinder, but also related to the printing viscosity of the ink. As mentioned above, when the printing viscosity is too high, the fluidity of resin pigments and other substances is poor, which can not be evenly dispersed and easy to accumulate together. Under the relatively high-speed movement of the scraper and the cylinder, the scraper and the cylinder are easy to be damaged, which is prone to linear dirt. At the same time, because the resin is also in a supersaturated state, a large number of resins gather together, and the affinity of the resin to the drum, under the pressure of the scraper, the resin will stick tightly to the drum (the resin contains pigment), so there will be flake dirt. Generally speaking, ink printing viscosity is small, dirty version phenomenon is not easy to occur

however, if the printing viscosity of the ink is too small, it means that the content of organic solvents in the ink is high, while the resin, pigment and other components are relatively small, so that a smooth film cannot be formed during drying, and the print will turn white, become dull and lack luster. Therefore, if a print needs to have a better gloss, it is generally necessary to consider using a larger ink printing viscosity (13 ~ 19S, chaen cup 3), that is, there are relatively more resin and pigment components to meet the needs of the print

at the same time, when the ink is printed on plastic and becomes an ink film after drying, the wrapped pigment can be firmly attached to the plastic surface, and resin is the main material for firmly attaching to plastic. Therefore, the fastness of pigment bonding is also related to the printing viscosity of ink. This shows that the proportion of resin and pigment in the ink should not be too large or too small, but should be within the normal range, and the pigment bonding firmness is large. Under normal environmental humidity, the printing viscosity of ink is above 16S (chaen cup 3) for the application of electronic universal testing machine, and electrostatic phenomenon generally does not occur. The printing viscosity of ink is below 16S (chaen cup 3). With the decrease of viscosity, electrostatic phenomena such as beard, stripe, edge rejection, flying ink, poor transfer, and extremely irregular water stains of pigment will occur and worsen

in view of the above reasons, insiders believe that the ideal state point of ink printing viscosity is generally found between 11 ~ 17s (chaen cup 3). If there is static electricity within this range, based on the principle of giving consideration to each other, it is generally not necessary to eliminate static electricity by increasing the printing viscosity of ink, but by maintaining normal environmental humidity, changing the composition structure of diluent, installing anti-static brushes, using anti-static agents and other methods. In this way, we can improve efficiency and yield while ensuring quality, and lay a necessary foundation for printing enterprises to obtain profits

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