Viscoelasticity refers to the performance that the ink is sheared and broken after being pressed by the scraper, the screen plate bounces up, and the ink rebounds quickly. The ink is bonded to the substrate, but it is separated from the screen, and the phenomenon of rapid retraction appears, which is a typical phenomenon of ink viscoelasticity.
The viscoelasticity of the ink has a greater impact on silk screen printing is the phenomenon of stringing. The drawing phenomenon is that when the squeegee scrapes and the screen bounces up, many ink filaments appear between the screen and the substrate. This is the most common phenomenon in screen printing, which not only makes the printed matter and stencil sticky, but also makes the printing impossible.
The length of the wire drawing is related to the viscosity of the ink. The higher the viscosity, the longer the ink filament, and vice versa. For this reason, viscosity reducers are often added or the relative molecular weight of the resin is reduced to reduce the viscosity of the ink, improve the viscoelasticity of the ink and reduce the stringing phenomenon.
The drawing phenomenon is also related to the time of the force. For the same ink, if the separation speed is fast and it splits elastically, the ink filament will be short; if the separation speed is very slow, the ink will flow down like a pure liquid without forming a filament.
