Paper Static Solutions
Eliminating the problem of paper static has always been an important issue that the paper industry and the printing industry are concerned about and urgently need to solve. This is because the paper has such an attribute that when its water content is high, the electrical conductivity is increased; conversely, when the water content is low, the insulating property is increased, and in this case, the paper is more prone to static electricity.
In the process of paper production, processing and printing, sometimes paper or prints are attracted to each other and stick together, which is difficult to separate. This is the phenomenon of static electricity. In the dry spring and winter, this phenomenon is particularly prominent, which can cause obstacles to normal paper feeding, delivery and papermaking, but not to start. Therefore, understanding the static electricity generated in the process of paper processing and printing and mastering the coping methods have very practical significance for maintaining production normalization.
The papermaking process is not easy to electrostatically charge the paper. In the process of papermaking, due to the low content of electrolytes (such as alum, sodium chloride, etc.), the content of sizing substances is too much, the content of some fillers (such as kaolin) is too small, and the paper is subjected to high temperature during drying and calendering. And the role of pressure to make the paper with a high voltage of static electricity. Improper storage of paper can also generate static electricity. When there is a large disparity between the temperature of the paper library and the temperature of the printing workshop, the variation of the moisture content of the paper not only causes the expansion and contraction to affect the registration, but also easily causes static electricity. In addition, the paper placement time before printing is too short, the paper and the printing environment lack an effective balance between temperature and humidity, and the paper stack pressure is too high and too heavy, which may cause the paper to be electrostatically charged.
Friction in printing causes static electricity. When the water content of the paper is too small, the paper is very dry, and the paper is subjected to friction and pressure during paper feeding and imprinting to cause the paper to be electrostatically charged.
There is a cause of static electricity on the paper, and some are caused by several situations, and the situation is different. The static electricity of various papers or batches of paper is not necessarily the same. Another feature is that the opposite sides of the paper have opposite polarity when the paper is charged, and the papers that are in contact with each other are firmly attached to each other and are not easily separated. Therefore, it brings obstacles to printing paper feeding, conveying and aligning paper, which not only affects production efficiency and product quality (such as tying faults such as over-blotting and misregistration), but also increases print loss.
In order to prevent the occurrence of static electricity, it is better to combine the paper temperature, increase the water content and use the static eliminator. The main measures are:
1. Install an air humidifier such as an air humidifier in the printing workshop to adjust and maintain the printing workshop at a constant temperature and humidity according to the static electricity of the paper. Under normal circumstances, the workshop temperature is adjusted between 18 ° C and 20 ° C, and the relative humidity of the air is maintained between 60 and 65%. If the paper is charged more strongly, adjust the relative humidity of the air to between 80-85%.
2. Install a static eliminator on the printing machine to eliminate static electricity on the paper. The static eliminator is adjustable to eliminate paper static by adjusting the voltage and frequency. Use high voltage and high frequency when the paper is static. When the paper is not static, turn down the voltage and frequency.
3. The isotope emitter is used to eliminate the printing static electricity. The principle of the isotope emitter and the static eliminator to eliminate static electricity is basically the same, and some of the air molecules are ionized into ions. Because the ions have different charges, when the paper passes through the ion space, part of the electrostatic charge will be neutralized, thus achieving the purpose of eliminating static electricity.