How To Eliminate Static Electricity During Production?

Excessive static electricity in the printing workshop has a lot of impact on production, which troubles almost every printing company. For different situations, there are many corresponding solutions, how to let the actual operators of the workshop fully grasp, continuous summary and integration is the key, so that each operator can make the right response when encountering corresponding problems. The author has sorted out some electrostatic elimination methods, and readers are welcome to continue to add.

First of all, let's take a specific look at what happens when the static electricity is too large? For example, the basic quality of the product cannot be guaranteed; Full page printing is easy to form "explosive" small white dots; Line drawing is easy to produce at the color block of the screen print, especially the double-transparent material is more obvious; PE materials can easily lead to inaccurate sockets; In-mold standard, double transparent material, cut sheet is not easy to sort out, causing chaos on site...

So, when the above situation occurs, how to eliminate static electricity? The author specifically summarizes the following methods:

1. Control the temperature and humidity of the workshop

First, determine whether the temperature and humidity storage of the material warehouse and the printing workshop are within a relatively suitable value. Usually the temperature is controlled at 20 °C ~ 25 °C, the humidity is controlled at 50% ~ 65%, and the raw material warehouse and printing workshop are required to be as consistent as possible. In order to ensure that the moisture content of raw materials does not change as much as possible. The change in the moisture content of raw materials is a process of discharging static electricity.

Temperature and humidity have a great influence on printing. When the temperature of the workshop is high, the flow performance of the ink increases due to the increase of temperature and the action of mechanical force, the molecular gravity between the inks becomes weaker, and the water consumption in printing will increase, which will accelerate the occurrence of emulsification, and it is easy to dry water paste plate in printing; When the temperature is low, the viscosity of the ink is large, the ink is more difficult, and an appropriate amount of additives must be added to the ink during printing to reduce the viscosity of the ink to ensure the printing progress; When the humidity is high, the paper is easy to absorb water and deform, and the amount of water is difficult to control when printing, and it is easy to have large water, so it is necessary to control the temperature and humidity of the workshop for printing. In the printing process, the temperature and humidity of the printing workshop can be reasonably controlled, the temperature change does not exceed 3 °C, in addition to preventing static electricity, the overprinting inaccuracy formed by the paper expansion and contraction will also be improved.

As mentioned above, the standard of printing requires that the ambient humidity is best controlled between 50% ~ 65%, but in winter, especially in the northern winter, the workshop humidity of many printing enterprises is difficult to achieve, and even 40% can not be reached, and mopping is the cheapest treatment method However, it is difficult to accurately control the humidity, and the installation of atomization humidifiers is one of the good solutions. An atomizing humidifier is installed at the discharge, winding and cutting station before printing, and when the overall humidity of the printing workshop is less than 50%, the atomization humidifier is started to ensure the overall humidity environment of the workshop. Special attention should be paid here that the humidifier must be mist, and there should be no large water droplets spraying out, otherwise falling on the raw materials will cause poor printing.

2. Install an electrostatic eliminator

If there is any simple way, then the "grounding" elimination method is the simplest operation. A metal conductor is used to connect the substance to eliminate static electricity with the earth, so that it is at the same potential as the earth, and the charge is conducted through the earth and disappears.

The common way is to install an electrostatic eliminator (rod type and hair dryer type) on the printing equipment to remove the static electricity generated on the printing material, the principle is to generate an electric field near it under the action of high voltage electricity, so that the molecules in the air split into positive and negative ions, and when the material with excess charge absorbs the corresponding ions through the electric field, neutralizes it, and then eliminates static electricity.

There are two main types of electrostatic elimination devices, one is electric, relying on a large number of ions in the electric field generated by it to absorb, neutralize and eliminate free electrons on the surface of the film to achieve the purpose of eliminating static electricity; The other is the discharge type, which does not require any energy to work, as shown in the figure, when the film passes through the metal wire, the excess electrons on the surface of the film enter the earth through the metal wire and disappear. Because the potential of the metal wire is lower than the potential of free electrons on the surface of the film, the film can achieve the effect of eliminating static electricity after the metal wire is discharged. The electrostatic elimination device is a very practical type of device in the printing process of film self-adhesive materials, and can be installed in multiple locations of the printing equipment according to requirements, such as before and after the die-cutting station.

3. Control printing pressure

The printing process is to complete the transfer of ink to paper by the pressure of the roller, and the pressure is large enough to make the ink of the print firm and clear, but at the same time generate a lot of static electricity. Reducing printing pressure can reduce the migration of paper charge and reduce paper static electricity, but it will affect the quality of the printed matter. Therefore, under the premise of ensuring normal printing, controlling the size of printing pressure is also one of the ways to eliminate static electricity.

Of course, the reduction of speed will directly affect production efficiency, increase the printing cycle, and need to increase the number of shifts or printing machines, and the balance between this is the wisdom of the captain.

4. Chemical elimination

Chemical elimination generally refers to coating a layer of antistatic agent on the surface of the substrate to make the substrate a slightly conductive insulator. There are great limitations in the application of chemical electrostatic elimination methods, such as adding chemical antistatic agents when printing the material of paper, which has a certain impact on the paper and thus affects the quality of printing. It will reduce the strength, adhesion, tightness, tensile strength, etc. of the paper, so the chemical method is not widely used.

The above are some of the methods of use summarized by the author in the work, and the shortcomings are welcome to criticize and discuss, so that this memorandum is more perfect and benefits more enterprises.