Plastic film prepress (2)

The coating made of the above formula is coated on the surface of the plastic film, air-dried for 10s, and irradiated with a high-pressure mercury lamp for 15s. After curing, the surface tension of the film can be increased.
3. The simple method of measuring the surface tension is determined by measuring the known surface tension of the absorbent cotton ball (see the following table) and coating it on the corona-treated film. The coating area is about 30mm2, and it shrinks into a water sphere in 2s. Then, the corona treatment intensity of the film is insufficient, and the corona strength needs to be increased again for impact. If the test solution does not shrink in water mark within 2 seconds, it indicates that the film has reached the treatment effect. Film printing requires a surface tension of 38 x 10-3 N/m (38 dyn/cm).

11dyn/cm=10-3N/m.
Third, anti-static treatment of static electricity in the printing of plastic film will bring a series of problems to the operation, a direct impact on the output and quality of printed products. For example, when printing small packaging plastic films, due to electrostatic adhesion, the films are in anoxic state, which will hinder the curing process of the plastic ink layer. In case of high temperature and high humidity environment, the adhesion of the ink layer is more likely to occur, and the color of the printing ink is lighter. Dyeing, increasing the difficulty of printing, slitting, finishing and other processes, when the film adheres to each other, tearing does not open, causing the printing products to be scrapped. In addition, the bag will be discharged during storage, storage and storage, which will not only affect the heat seal but also affect the transparency of the physical and space layers in the bag. When a large-format film is printed, a large number of static electricity is generated, and if the machine speed is high and the antistatic agent is not incorporated in the resin, it is likely to cause a fire or an explosion.
The static electricity of the plastic film is due to the excellent dielectric properties of PE and PP, high resistance, and poor conductivity. The film generates static electricity due to friction during the winding process of extrusion, which causes static electricity to be further generated and accumulated in the printing process. Release, causing the film surface to accumulate a large amount of static charge. After the printed film is wound, the film and the film are tightly wound together, so that the electric charge is not conducive to repulsion and is conducive to attraction, resulting in adhesion.
Paper printing can eliminate static electricity through static eliminators, but this method has little effect on plastic packaging printing.
Plastic packaging generally uses anti-static agent in the ink to eliminate static electricity. Commonly used antistatic agents include general surfactants, functional group polymers, and organic or inorganic salt compounds. These substances have weak ionization properties and can produce antistatic effects on plastic films. According to relevant data, Japan uses an ion generator to produce cations and anions on the surface of plastic films through nozzles, which can also achieve the effect of handling static electricity.