Positive and Negative Charge Separation Technology of Gravure Printing

Each substance consists of a positively charged nuclei and an extranuclear electron that rotates negatively around the nuclei. In an uncharged object, the positive charge of the nucleus in the object is just balanced with the negative charge of the electron, and the charge is neutralized, so there is no electrical property. However, if two objects are in close contact, the electrons can easily be transferred from one object to another, so that the power will be unbalanced and the objects will be electrically charged. Especially when two objects rub, this close contact is more obvious, so we often call it frictional static electricity.

In the contact area, the object that loses electrons is positively charged, and the object that receives electrons is negatively charged. This is charge separation, but the voltage and power generated by this charge separation are very small.

The second most common charge separation mechanism is electrostatic induction. When an electrically conductive object is placed near a charged object, the object will have a charge separation. The same charge that is repulsed to one end by the original charged body may be directed to ground by the grounding switch. At this point, the uncharged object is charged with the opposite charge from the original charged body. At this time, if the inductive charged object is separated from the ground, a higher voltage and power will be generated. Inductive charging is considered to be the most important reason for the large amount of static electricity and electrical energy accumulated in the printing process. In addition, if the electrical conductivity between the shoe and the floor is not good, even if the printed part is connected to the ground, the human body will still bear the charge when it touches the printing press.

Similarly, if a charged object is close to a grounded metal component or container, the corresponding surface of the metal component or container is also sensed and charged with the opposite charge. In this way, although they are 0 voltage (because it is followed), they are charged. In the same way, the surface of the solution is also charged like this. Therefore, unless all the containers are grounded, static sparks will be generated when a part of the solution is poured out.

The third mechanism of charge separation is the separation of droplets. The molecular structure of liquid will cause the difference between the liquid surface and the internal voltage of the liquid. Even if there is no externally charged object, the liquid surface rupture will lead to the charge separation. Due to the strong polarity of water molecules, the static electricity generated by this mechanism is evident in high-speed flow of wet steam and wet compressed air.