During the printing process, sometimes the paper or printed matter will stick to each other, as if the paper surface has a strong vacuum suction, it is difficult to separate, this phenomenon is printing static electricity. In the dry climate in winter, the static of the printed paper is particularly prominent, ranging from obstacles to paper feeding, paper collection and flushing, and heavy paper failures such as automatic paper feeding or frequent double sheets, empty sheets, paper delivery disorder, increased loss, etc. As a result, both reduce production efficiency and affect product quality. Therefore, it is of positive significance to correctly understand the printing static electricity and master the countermeasures to promote production.
When the paper contains a high amount of water, it can become a conductor of electricity; on the contrary, when the water content is very low, it is absolute, and the reason why the paper is prone to static electricity: First, the papermaking process is not suitable. That is, during the papermaking process, due to the low content of electrolytes (Ming ?, sodium chloride, etc.) and the excessive content of sizing materials (high territories, etc.), the paper is subjected to high temperature and pressure during the drying and calendering process. Make paper with high voltage static electricity. The second is improper storage of paper. For example, when there is a large disparity between the temperature of the paper car and the temperature of the printing workshop, due to the variation of the moisture content, the paper does not even have a stretch to affect the registration, and it is easy to cause static electricity, which causes inconvenience to the brush. In addition, the paper placement time before printing is too short, or the stacking is too high, so that the paper and the printing environment temperature lack of effective balance time, causing static electricity on the paper. The third is printing friction caused by static electricity. When the water content of the paper is obviously too low, the paper will be too dry. During the printing process, due to the friction and pressure of paper feeding and imprinting, the electrons outside the paper nuclei will gain and lose, making the paper static.
The paper is static, and the situation is different. There is a cause, and there are several types of undesirable conditions that are concurrently formed. All kinds of paper, even the same kind of paper, this batch and the previous batch, the size of static electricity is not necessarily the same, that is, the voltage level will be different. Another feature is that the paper is electrostatically charged on both sides, and the front and back sides of the paper are the same when printing, that is, the front side is facing up or the back side is facing up. Therefore, the paper that is in contact with the front and back sides is firmly adsorbed to each other, which is not easy to separate, which brings certain obstacles to printing, conveying, conveying, and aligning paper.
To prevent the occurrence of printed static electricity, we must first control from the source. The paper with static electricity can be used for a while, the storage time should be properly extended, and the temperature and humidity of the paper warehouse should be controlled at 18 ℃ ～ 20 ℃, and the relative humidity of the air should be controlled at 60 ～ 65%. It is helpful to reduce or eliminate paper static electricity. Secondly, use paper drying method to remove paper static electricity. When the paper is urgently used, a paper dryer can be used to hang and dry the paper with static electricity. When lifting, you should pay attention to the coordination between the machine speed and the air humidity, that is, when the machine speed is fast, the relative temperature of the ambient air is controlled at 80-85%, otherwise, the air temperature is maintained at 70-80 when the machine speed is slow %. It should be noted that: when hanging, the thickness of each stack of paper should be controlled within 10mm. Third, the emergency drying paper removes static electricity. Static electricity appears when printing on the cut paper. You can use the "steam method" to quickly dry the paper to reduce the static electricity of the paper and complete the printing as soon as possible.
To eliminate paper static electricity, you can also use a comprehensive method of elimination, that is, to increase the paper temperature, moisture content, and the use of static electricity eliminators, the effect will be better. The method is:
1. Install air-conditioning equipment in the printing workshop, adjust or maintain the temperature and humidity of the printing workshop according to the strength of the paper static electricity. In general, the temperature of the workshop is adjusted between 18 ° C and 20 ° C, and the relative air temperature is maintained between 60% and 65%. If the paper is heavily charged, the relative humidity of the air can be adjusted to between 80 and 85%.
2. Install a static eliminator on the printing press. Eliminate the static electricity of paper by adjusting the voltage or high frequency. If the static electricity of paper is large, use high voltage or high frequency. If the static electricity is not large, lower the voltage and high frequency.
3. Eliminate printed static electricity with an isotope emitter. The principle of isotope emission and static electricity of static eliminator is basically the same, all of which ionize various molecules in the air into ions. Because ions have different electrical properties, they become good conductors of electricity. When paper passes through the ion space, part of the static electricity Being neutralized, the other part is taken away by air ions, so as to achieve the purpose of eliminating static electricity.
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