![]() ![]() ![]() What is the result of working with normal viscometers at constant viscosity when the ink temperature changes?Ī job with an ink at 25 ° Celsius and 25 ”in Ford 4 cup (suppose with a dilution of 20%), by adding colder ink at the same dilution, for example at 20°, we will obtain a viscosity of 30”, more high not because of the change in dilution that is maintained at 20%, but because the ink at a lower temperature flows worse (its viscosity increases). This happens in countless materials, such as oils, plastics, wax, fats of all kinds: at higher temperatures they flow better (they have a lower viscosity). Let’s see what happens with an example:Ī 25 ° centigrade ink, diluted by 20% (for example), has a viscosity of 28” in a Ford 4 cup, that same ink with the same degree of dilution at 30 degrees will have a viscosity of 24”, lower. The problem is that the viscosity of the inks can vary not only by the difference in the amount of solvent in the mixture, but also by temperature changes. A fact that normally does not happen, since the printing process itself raises the temperature of the inks. Once an automatic viscosity meter is installed, maintaining the color is very simple, as long as the ink is kept at a constant temperature. Viscosity meter for inks of body drop that measure the time it takes for a body immersed in the ink and confined in a tube, usually glass, where longer times correspond to higher viscosities. ![]() Vibration viscosity meters (also called ultrasound), a palette vibrates inside the ink reaching a different frequency for each viscosity.At more viscosity there is more pressure. Line pressure reading systems: a sensor in the conduit that carries the ink and measures the pressure exerted by it.It is the simplest but the most imprecise system. Systems based on the working frequency of a pneumatic pump when sending ink to the printer.Currently, they are more sophisticated electronic systems, used in different technologies to measure viscosity: Said container has different names and numbers, depending on the shape and size of the discharge hole. At first, they were manual systems like the Ford or Zahn cups, based on the time needed for an ink to discharge from a container (the cup). Viscometers, over time, have been adapting to the needs of the sector. The evolution of the viscosity meter for inks We have then an easy way to control and maintain color by using viscosity meters. ![]() Therefore, by keeping the viscosity constant we will have a constant solids concentration and, therefore, the same color on the printed support. The same does not happen with the solvent that does evaporate and, therefore, changes the proportion between this and the solids responsible for the color, thus modifying the tone or intensity obtained.įrom all of the above we understand that maintaining the solid-solvent ratio allows us to obtain a constant color, and this ratio is directly proportional to the viscosity of the ink. Of these three main components, the ratio between the resin and the pigment is fixed, since they do not evaporate and are consumed at the same time. The ink is, in essence, a mixture of pigment that provides the color and resin that fixes the pigment onto the substrate and the solvent that gives the ink an adequate viscosity or flowability to be able to move from the chromed cylinder to the gravure material, as well as from the anilox cylinder to the cliché, and from this to the support to be printed on via flexography. Today we will talk about the viscosity meter for inks. From the beginning, the flexible material printer, using flexographic or rotogravure techniques, has had the need to control the color obtained in this process, which is called conversion. ![]()
0 Comments
Leave a Reply. |