Different printing processes have different requirements for ink. According to the actual use of ink, some supplementary components are added to the ink. For example, offset printing ink has large viscosity, good water resistance, gravure printing ink is relatively thin and has good fluidity; Screen printing ink must have good permeability.
In terms of substrate suitability, screen printing has great advantages, especially in the amorphous plastic, hardware, electronics and direct consumer goods industries. However, screen printing can not cope with the industrialized printing field of small area and irregular substrate surface, so it gave birth to pad printing technology. Although the processes of silk screen printing and pad printing are different, their industrial fields are indeed very similar.
The initial pad printing process used the same ink as silk screen printing, but the ink used in different printing environments has different adaptability. For example, the user does not require the pad printing ink to have the permeability of silk screen printing ink at all, but will require it to have better thixotropy and surface dryness, so as to ensure that the transmission process from steel plate to rubber head and substrate is more accurate. The use of special pad printing ink will undoubtedly make it easier to improve the printing quality.
Foreign ink manufacturers took the lead in developing special pad printing ink, which keeps the surface tension of ink in a constant range through the action of additives, so as to keep the ink transfer consistent in the printing process. The process of ink transfer is also closely related to the properties of the pad printing head. The purpose of controlling the surface tension of the pad printing head within a range similar to that of the pad printing ink is to improve the ink transfer efficiency.
In addition, it is worth noting that silk screen printing ink and pad printing ink are completely universal, but additives need to be added to change the printability. Therefore, when there is no special pad printing ink, silk screen printing ink can be used instead.