There are many methods for pre-printing surface pretreatment of plastic film printing machine, which can be generally divided into chemical treatment method, flame treatment method, corona discharge treatment method, ultraviolet radiation treatment method, etc. The chemical treatment method is mainly to introduce polar groups on the surface of the film, or use chemical reagents to remove the additives on the surface of the film to improve the surface energy of the film.

The working principle of the flame treatment method is to let the plastic film quickly pass 10-20mm away from the inner flame, and use the temperature of the inner flame to stimulate the air to generate free radicals, ions, etc., and react on the surface of the film to form new surface components and change the film. surface properties to improve adhesion to ink. The treated film material should be printed as soon as possible, otherwise the new surface will be passivated quickly, which will affect the treatment effect. Flame treatment is difficult to control and has now been replaced by corona discharge treatment.

The working principle of corona discharge treatment is to pass the film through a voltage field, which generates high-frequency oscillating pulses that force the air to ionize. After ionization, the gas ions impinge on the film to increase its roughening.

At the same time, free oxygen atoms combine with oxygen molecules to generate ozone, and polar groups are generated on the surface, which ultimately increases the surface tension of the plastic film, which is conducive to the adhesion of inks and adhesives.