From the analysis of the formation mechanism of printing fastness and test methods, we can better understand the way to improve the printing fastness (mainly on the polyurethane film for discussion).1. Selection of raw materials In the production of plastic film should be selected when the raw material does not contain or less plastic additives. We can judge the content of additives according to the technical information about the grade, performance and use of the resin. When we have to use raw materials containing more additives, we should also mix them with those without additives. The reason for this choice is that in the process of forming and placing the folding out of the additives will form a film of oil, thus weakening the adhesion of the ink on the film.2. Raw material modification 1) blending modification: polyolefin and printing performance of polymers blended to improve printing performance is a newly developed compelling method. For example, with polyacrylic resin modified high-density polyethylene greatly improve the adhesion of ink to polyethylene, when which is mixed with 5-20% of polymethacrylic acid early ester (PMMA), the above-mentioned adhesion increased by seven times. Again, such as with more chlorine content of chlorinated polyethylene work mixing, only a small amount can be added to significantly improve the adhesion of polyethylene and oil black. When mixed with 5% CPE-55 blends and ink bonding than (chun) HDPE three times higher. According to another report, some plastic polymer processing aids (rheology modifiers, etc.), in addition to improve yield, eliminate melt rupture, but also has to improve the role of printing adhesion. Add polyacrylic acid resin or chlorinated polypropylene and other reasons to improve the printability of HDPE is based on their poor compatibility with HDPE, when it is in the HDPE as the substrate of the blending system constitutes a dispersed phase and live in the open film surface layer, is obviously conducive to the adhesion with the ink. (2) grafting modification: grafting modification is the use of radiation and other methods to make the polyolefin points to grafting reaction so as to make the polyolefin macromolecular chain with polarity and thus improve the wettability of the material to the ink. Such as maleic anhydride or acrylic acid graft modification of linear density polyethylene after the improvement of its printability. 3) other methods of modification: such as in the polyolefin doped with a small amount of maleic anhydride or its anhydride, but also to a greater extent to improve the polyolefin film ink fastness to print.3. Printing ink fastness in the printing ink fastness problem, the ink also plays a decisive role. Of course, for different substrates should use its corresponding ink. For example, for cellophane can use nitro cellophane resin ink; for polypropylene film can use chlorinated polypropylene resin ink; for polyethylene film can use polyamide resin ink, and so on. I...
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