The important influence of ink rheology on printing quality is discussed
The rheological properties of the ink include the viscosity, adhesion, yield value, thixotropy, fluidity and fluidity, and transferability of the ink. In the printing work, the rheology of the ink has an important impact on the quality of the printed product. The following are to talk about the impact of these rheological properties on the printing quality of ink. First, viscosity. Viscosity is a measure of the ability to hinder the relative movement of molecules caused by the mutual attraction of fluid molecules, which shows a property of preventing flow in the fluid and the degree of resistance to flow. The motion resistance caused by the mutual attraction between fluid molecules in the process of fluid flow is called internal friction. Viscosity is an important indicator of ink rheology, in the printing process of a certain viscosity is to ensure that the ink support transfer and uniform transfer of the main conditions, it is related to the printing process can proceed smoothly, and directly affect the uniformity of ink, clarity and gloss. Improper control of ink viscosity in printing will bring a variety of failures to printing, as listed below. 1.When the viscosity of the ink is too large, the drawing property is strong, during the ink transfer process, the wire head is too long when it splits between the ink rollers, and the broken end of the wire head is easy to form the ink flying into the air, forming the flying ink phenomenon in printing, and the flying ink phenomenon is more obvious in high-speed printing. 2.the viscosity of the ink is too large, it is easy to cause the depowder of the paper, drawing or delamination stripping phenomenon. This phenomenon is particularly obvious when the structure of the printing paper is loose and the surface strength is not high. 3, when the ink is transferred and transferred between the ink rollers, the viscosity is too large to make the ink transfer difficult. Excessive ink viscosity will lead to uneven distribution of ink, insufficient ink transferred to the plate or printed matter, uneven ink, and the phenomenon of bare print graphic base. Other effects of excessive viscosity on the printing process, such as the increase in the amount of ink, the printing ink layer is too thick, the drying speed is slow, and the back of the printing matter is easy to stain or adhere; In flat paper printing, it is also easy to produce the phenomenon that the paper is sucked into the ink roller. 5.the viscosity of the ink is too small, its fluidity increases, and it is easy to produce ink emulsification in the offset printing, resulting in dirty prints; The ink with too small viscosity is easy to produce spreading phenomenon on the paper, resulting in a large imprint area, a decline in clarity, and reduce the firmness of the combination of the imprinted dry conjunctiva and the substrate surface and the gloss of the imprint. 6.The viscosity of the ink is too small, often can not drive the ink particles in the larger p...
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