Since polyethylene is a typical non-polar high molecular material, its molecular structure does not contain polar groups, and its crystallinity is high, its surface free energy is low, its inertness is strong, its crystallinity is high, and its chemical properties are stable. Therefore, the film material The printability is poor and the adhesion to the ink is not ideal. In addition, the additives (slip agents, plasticizers, etc.) in the film constantly migrate to the surface to form a weak surface layer, which also affects the printing fastness of the printing ink. Therefore, the plastic film is generally required before printing. Surface treatment, change the chemical structure of the film surface, improve the surface tension of the film, so as to achieve the purpose of improving and improving the printability of polyethylene film, improve the adhesion of the ink to ensure the smooth progress of production.
The surface treatment technology of plastic films currently used in industry in China is corona, but the limitations of this method are large, and it is not applicable to many large-scale applications. Plasma surface modification technology has been listed in the national "863" plan, but no technical breakthrough has been made so far. The main reason is that the high vacuum required by this technology makes it difficult to become a surface modification technology for bulk industrial products to solve the existing Film products and production problems.
Recently, Beijing University of Chemical Technology has developed a new continuous production process for preparing hydrophilic/hydrophobic asymmetric plastic films with surface light grafting as the main technical feature. The plastic film product obtained by the new surface treatment technology still has the original hydrophobicity of the film on one side, and the surface polarity can be arbitrarily adjusted on the other side according to different needs until it is completely hydrophilic. Of course, both sides of the film can also be processed simultaneously to obtain a symmetrically modified product.
Corona treatment of plastic film surface
July 23 08:01:02, 2024
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