Six effects of the viscosity of the hottest ink on

Six effects of ink viscosity on gravure printing quality

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core tip: in plastic gravure printing, the non printing surface of the printing plate roller is often adhered with a layer of hazy ink, and when transferred to the printing substrate, it often presents a sheet or line like dirty version, which is dirty version, also known as fog version. The cause of the dirty plate problem is not only related to the ink formula itself, the pressure and contact angle of the doctor blade and the quality of the printing plate, but also related to the printing viscosity of the ink

in plastic gravure printing, the non printing surface of the printing plate roller is often adhered with a layer of hazy ink, and the transfer to the printing substrate often presents a sheet or linear dirty plate, which is dirty plate, also known as fog plate. The cause of the dirty plate problem is not only related to the ink formula itself, the pressure and contact angle of the doctor blade and the quality of the printing plate, but also related to the printing viscosity of the ink

if the printing viscosity of the ink is too high, the viscosity of the ink will become larger. Under the high-speed movement of the printing plate, the ink will produce a great impact on the doctor blade. In this way, it is difficult for the doctor blade to scrape off the ink of non graphic parts smoothly, resulting in version pollution

if the pigment in the ink is unevenly distributed in the ink system, or the resin in the ink fails to wrap the pigment particles well, the pigment particles will regroup. The formation of human pigment groups (i.e. coarsening phenomenon) these larger particles are easy to form linear or strip knife lines in printing

generally speaking, the lower the printing viscosity of the ink, the less likely it is to cause the problem of dirty plate. Therefore, in the actual printing process, special attention should be paid to the change of the half occupancy of the printing ink, and the printing viscosity should be adjusted in time to improve the print quality

second, the problem of flying ink in high-speed printing:

when the gravure printing speed exceeds 20m/min, if the domestic chlorinated polyene resin with wide molecular weight distribution is used in the gravure printing ink, resulting in the low viscosity of the printing ink, it may cause the problem of "flying ink". The reason is that the viscosity of printing ink is too low. The cohesion of the ink decreases significantly. When the ink is transferred to the printing brush film, the low molecular weight resin is easily separated, and a small "ink dot" can be seen in the blank part of the print

the problem of "flying ink" can be solved from the following two aspects: first, chlorinated polypropylene resin with narrow molecular weight distribution; Second, according to the printing situation, appropriately improve the printing viscosity of the ink

III. Influence on color, transfer rate and color saturation:

intaglio ink is transferred to the printing substrate by the ink of the concave point of intaglio. Relatively speaking, the volume of the printing point is basically fixed. With the increase of ink printing viscosity, the viscosity of the ink also increases, and the more ink is transferred from the point, so the color concentration and saturation of the print are higher, but there is a certain limit

when the viscosity of the ink continues to rise to a certain extent, the transfer rate of the ink has also reached a synchronous increase. If the viscosity of the ink continues to rise, the viscosity of the ink will become stronger and stronger, and the ink will begin to be difficult to enter a small point. The ink responsible for reviewing the overall deployment and important plans to promote the development of the new material industry will become less and less, The transfer rate of ink began to decline step by step (2) new material project innovation demonstration project. The color density of printed matter also began to decline. The ink manufacturer suggests that the printing viscosity of gravure ink is generally 13 ~ 22 seconds (3 × chaen cup), which is only an empirical value. In the actual printing process, in order to achieve a good printing transfer effect. Choose printing viscosity carefully

IV. impact on printing speed:

the printing speed of the existing gravure printing machines in China (including imported and domestic machines) ranges from 30m/min to 300m/min. Generally, the printing speed of the printing machine is m/min. In actual printing, we should choose according to the printing speed of the printing machine. When the printing speed increases, the printing viscosity will decrease. Of course, the most suitable printing viscosity. It is also affected by other factors:

1. Even at the same printing speed, the printing viscosity will be different due to the difference of ink formula design. Therefore, in the actual printing process, it must be adjusted according to the printing effect

2. Affected by seasonal temperature: the viscosity of the same printing ink is different in summer and winter, and ink manufacturers have been working hard to reduce the impact of temperature on ink viscosity

3. Select the most appropriate ink printing viscosity according to the actual conditions of the printing plate roller

v. impact on Printing Crystal Gloss:

the lower the viscosity of gravure ink (that is, adding more solvents to the original ink), the lower the content of resin and pigment in printing ink. "1 BMW I3, whose body structure and frame are completely made of carbon fiber reinforced plastic, has attracted many people to visit. When the ink is transferred to the printing substrate and dried, it is not easy to form a smooth ink layer. The phenomenon of white flowers directly leads to the lack of gloss of printed matter. Therefore, in order to obtain excellent gloss, we must ensure that the printing ink has the appropriate resin and pigment content

VI. electrostatic problem:

generally, OPP internal printing ink has limited antistatic ability, which is easier to generate static electricity than polyamide surface printing ink and polyurethane system ink. For OPP internal printing ink, the higher the viscosity of the printing ink, the less likely it is to generate static electricity. Under normal temperature conditions, the viscosity of the printing ink is more than 16 seconds (3 chaen cup). Static electricity generally does not occur; If the printing viscosity is lower than 16 seconds/3 × cup, beard, stripe, edge rejection and other faults are easy to occur

if the viscosity of the printing ink has been within 15 seconds/3 cup, we suggest not to use the method of increasing the viscosity of the printing ink as far as possible, because increasing the viscosity of the printing ink will not only increase the printing cost, but also bring difficulties in printing transfer, which is prone to printing failures such as dirty plates. You can simply change some states and take other methods to eliminate static electricity according to the specific situation of static electricity, for example, by changing the proportion of diluted solvent. Adding 5% isopropyl alcohol (a polar solvent with good conductivity) or a small amount of antistatic agent as appropriate can achieve the purpose of eliminating static