Analysis of the stickiness of water-based inks.

Analysis of the stickiness of water-based inks
Water-based inks are made up of organic pigments, connecting materials, solvents and related additives mixed by physical and chemical processes, and the main difference with solvent-based inks is that the solvent used in water-based inks is not organic solvents but water, that is, water-based inks are mainly composed of resin and water. Ink and ink to print the ideal effect must have suitable for printing the working suitability. There are many factors affecting the suitability of water-based ink printing, the following mainly on the viscosity of ink, tentacles, adhesion, pH and paper ink absorption and other properties of the impact on printing suitability

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is the size of ink cohesion and the most important control index in ink application. In the process of printing, ink has a certain viscosity is to maintain its normal transmission, transfer of the necessary conditions: ink viscosity if too low, will cause light color, network expansion, high-gloss point deformation of ink uneassiad disadvantages; The factory viscosity of inks and inks varies from manufacturer to manufacturer or variety, - controlled in the range of 30-60s / 25 degrees C (with 4 paint cups). It is better to adjust the viscosity to between 40-50s when using.
For offset ink, can be reconcile between ink rollers, so that the ink is evenly coated on the plate, and the soft printing ink is only by its own fluidity, adhesion filling in the mesh roller mesh hole and transfer ink to the plate, and the ink must be filled in a very short period of time, only the lower viscosity is thin ink has such a nature.
if the viscosity is too large, it will cause the following
: ink transfer, transfer difficulties. Because the flexo printing machine is very fast, the first color printing to the second color printing, its interval is only a few seconds to zero seconds, requires ink viscosity is small, easy to separate, transfer fast, dry fast
practice has proved that under the same conditions, the split state of the ink layer with a small viscosity is more favorable to the transfer of the ink than the viscosity.
so flexible version of ink is generally less viscosity, its range is: 0.15-0.3Pa-s. But the ink viscosity can not be too small, otherwise easy printing will cause the ink in the dot easy deformation, so that the reproduction of the picture is worse. Serious will cause ink emulsification, or make it can not be normal transmission, transfer, and gradually in the mesh rollers, plates on the accumulation of pigments, when the accumulation reaches - a fixed degree will cause paste.
Generally for smoother prints, when the ink star is sufficient, the transfer rate is higher, so the viscosity of the ink is required to be slightly higher;
in actual production, when using a printing press with an ink scraper, the ink transmission star is not as stable when the temperature is too low as when the temperature is slightly higher. An increase in ink temperature will reduce viscosity, resulting in a decrease in print density and a dilution of the ink layer.
to maintain the print quality - the quality of the ink must be maintained consistent. Printers must attach great importance to the impact of ink temperature, before printing should be used to stabilize the temperature of the ink in the printing shop temperature. This measure is very important, otherwise the ink density in the printing process will vary greatly.
of water-like ink viscosity
1, temperature on ink viscosity
workshop temperature on printing quality, relative humidity in 60% to 85% better.
most sensitive to the performance of viscosity when the temperature difference is large in winter and summer. When the temperature is high, the water evaporates quickly, the drying is fast, in the operation, we should pay attention to extend the drying time or improve the machine speed, when the temperature is low, the water evaporation is slow, the ink is also slow, in the operation, can improve the ink drying speed or add the drying device. When used in winter, because the ink is easy to freeze below 0 degrees C, if the ink ice, can be placed in a room with high temperature, let it dissolve naturally, stirred well, can continue to use.
2, the effect of touch denaturation on ink viscosity
touch denaturation refers to the increase of fluidity under the external force stirring, the fluidity gradually decreases after stopping stirring, and restores the performance of the original condition. Ink placement time after a long time, some poor stability of ink easy to precipitate, layering. There is also the phenomenon of false thickness. At this time, can be fully stirred, after a certain period of time after stirring, the above problems naturally disappear. When using fresh ink, be sure to stir well in advance before making dilution adjustment. Or expect to a certain amount of ink on the machine, the degree of viscosity decline, because the machine contains water and ink tentacles can improve the flow of ink.
3, PH value on ink viscosity
ink applications in another need to control the pH value of the indicator, its normal range of 8.9.5, when the printing performance of water-based ink is the best, printing quality is the most stable. When the PH value is higher than 9.5, the alkalinity is too strong, the viscosity of the water-based ink is reduced, the drying speed is slower, the water resistance is poor, easy to paste version, and when the PH value is less than 8.5 that is, the alkaline is too weak, the viscosity of the water-based ink will increase, the ink is easy to dry, blocked to the plate and mesh rollers, causing the surface dirty, and produce air bubbles.
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