Elimination of paper static electricity in printing process

In printing, the static electricity on the paper can cause a lot of trouble. For example, when the entire paper is cut according to the specifications and printed on the machine, it must be bumped. With static electricity, under the action of static electricity, paper and paper are firmly held and the air is difficult to penetrate between the sheets. To neatly order the paper, it is often necessary to pull one by one by hand.

Printing

Due to the electrostatic attraction, the paper is closely attached to each other, and it may be impossible to separate the suction nozzles of the automatic paper separator. The brush is heavy, it is easy to produce broken sheets and empty sheets; the brush is lighter in pressure, and it will cause double or multiple sheets. Multiple sheets of paper will enter between the blanket cylinder and the impression cylinder, causing boring cars and crushed rubber. Cloth or pad. Paper with static electricity is not naturally conveyed at the paper feed station; it is prone to misalignment when it reaches the front gauge, and positioning is inaccurate. As a result, the overprint cannot be registered, resulting in waste.

At the time of delivery

Even if the static-charged paper passes through the embossing process, it is easy to collect the paper and cause trouble for the second time. Many objects are charged with static electricity caused by friction, paper is charged due to friction. Papermaking, paper and calender friction, printing, paper and rubber roller, the pressure between the impression roller ... ... are the cause of static electricity. So, how to eliminate paper static electricity?

One of the methods

After the paper is put into the warehouse, the storage time is as long as possible. The storage place can communicate with the printing shop better, the temperature is controlled at 18-25 degrees Celsius, the relative humidity is controlled at 60-70%, and the temperature, humidity, and print shop of the paper store are To achieve consistency, it is beneficial to change the moisture content of the stored paper. The change in water content of paper is a process of releasing static electricity.

Method two

During the printing process, a damp towel is placed on the delivery section, and the water-dried towel is fixed on the pull rod so that the paper is in contact with the wet towel when it passes through. This is a method used by many people to eliminate static electricity. A simple and effective method.

Method three

When the relative humidity in the workshop is less than 50%, high static electricity is easily generated during the printing or platemaking process. Therefore, increasing the relative humidity of the workshop and the moisture content of the paper, especially when the paper is being dried, increase the relative humidity in the room, which helps Eliminate static electricity. Increase the indoor relative humidity can use the humidity control equipment, there is no humidity control equipment can be used on the ground water and humidification method. Humidity equipment is mainly humidifier. The centrifugal automatic humidifier is installed on the ceiling or wall of the workshop. When the indoor relative humidity does not meet the requirements, the humidifier will automatically spray out misty water vapor to increase the relative humidity in the room. When the relative humidity in the room meets the requirements, Spray will stop automatically.

Method four

An electrostatic eliminator is used to neutralize the charges on the electrified body by the ions generated by the static eliminator so as to eliminate static electricity.

There are currently three types of static eliminators:

One is to eliminate radioactive elements. It uses the ionization of radioactive isotopes to ionize air-generated ions to neutralize static electricity on the charged body. One is an automatic discharge static eliminator. It is made of conductive fibers, conductive rubber or conductive metal materials, etc., and is made into a needle-like fine wire electrode and contacts well. The electric field of the charging body generates corona discharge generating ions to neutralize the charge on the charged body. There is also an external voltage type static eliminator. It generates high voltage by applying needle-like or thin-line electrodes and generates corona ions.

Method Five

Use antistatic agents (also known as static eliminators, removers). The principle of antistatic agents is to give hygroscopic ions on the surface of charged objects such as paper and film to become hydrophilic so as to absorb the moisture in the air, reduce the electrical resistance, increase the electrical conductivity, and make the electrostatic charge less likely to accumulate. Antistatic agents are mainly surfactants with hydrophilic and hydrophobic groups (or polar groups and non-polar groups). Hydrophilic groups have strong affinity for water and other polar substances, and hydrophobic groups have strong affinity for oils and other less polar substances. Antistatic agents have a wide variety of uses in printing, such as making soft rollers for preventing static electricity.