UV printing process and working principle of ink
UV printing is a printing process that dries and solidifies ink through ultraviolet light. It requires the ink containing photosensitizer to cooperate with UV curing lamp. UV ink has covered offset printing, silk, inkjet, pad printing and other fields. UV curing ink
UV curing ink is an ink that can instantly change from liquid to solid under the irradiation of ultra violet light waves, so it is also called UV ink. Its main components include photopolymerizable prepolymers, photosensitive monomers, organic pigments, photopolymerization initiators, and additives. Among them, photopolymerization initiator is the most important component of UV ink and the beginning of photopolymerization reaction. The commonly used photopolymerization initiators are aromatic ketones and so on. Curing/drying principle of UV curing ink in Yonghui supermarket, Qianshan Road, Hefei the main reason for UV ink curing is that under the irradiation of ultraviolet light, the photopolymerization initiator in UV ink absorbs photons of a certain wavelength and turns into free molecules, which become free radicals. Then, through the transmission of energy between molecules, the polymeric prepolymer and optically active monomer become excited, Charge transfer complexes are generated, and the complexes are continuously crosslinked and polymerized to solidify into films
The curing process of UV ink is a photochemical reaction process, that is, under the action of UV energy, the prepolymer solidifies into a film in a very short time. In addition to causing the surface curing of the ink, UV can penetrate into the liquid UV curing ink and stimulate the further curing of the deep ink film. In traditional inks, oil-based inks solidify under oxidation, while solvent or water-based inks solidify mainly by evaporation of water or solvent, and some inks can penetrate into paper. Therefore, compared with traditional inks, UV curing inks are more thoroughly polymerized and dried without any evaporation or solvent pollutants, and the ink film is 100% curedmain characteristics of UV curing oil quantity
1. Excellent drying performance. Because UV ink can only be dried under the irradiation of ultraviolet light, even if the ink is stored in the ink bucket for a long time, its performance can remain stable, and there will be no scaling on the ink roller. Moreover, once irradiated by ultraviolet light, the ink can be instantly dried and completely cured. Its curing time is very short. Generally, it only takes 1/10s to completely dry and fix on the surface of the substrate. For traditional thermosetting ink and sheet fed offset printing ink, the drying time may take a few minutes, or even a few days to completely dry. Therefore, printing live parts with UV curing ink has a short delivery time, which is comparable to flexo printing and gravure printing, And greatly improve the production efficiency of printing
2. It is conducive to the post-processing process. After UV ink printing, UV polishing and machining are carried out, and the printed matter obtained has high gloss, and the surface is flat and uniform. After the machine is polished, the packaging processing processes such as die cutting, indentation, gluing and bronzing can be completed immediately, which is very conducive to the development of high-speed printing. 3. Accuracy of experimental force: ± 1%
3. Good durability when labor pains are relatively concentrated and sharp. UV curing ink not only can provide bright and bright colors, but also has strong abrasion resistance. The chemical substances in UV ink form a high molecular stereoscopic polymer through cross-linking reaction. Therefore, the use of UV ink can make the ink layer of printing strong, fast drying and cross-linking. Such an ink layer has high abrasion resistance and chemical resistance. Many prints printed by UV ink on coated paper for direct mail can withstand multiple folds and can withstand the strong radiation during laser printing again. Therefore, UV ink can be used for outer packaging printing that requires wear resistance
4. Good environmental protection performance. Another important feature of UV curing ink is its environmental protection performance because the inspected surface of the sample coincides with the surface of the workbench. Because the solid content of UV ink after curing is close to 100%, it contains almost no VOC (organic volatile matter), that is, it will not or rarely emit volatile organic compounds during the curing process, will not cause harmful environmental pollution, and will waste less and save energy, There is no need to worry about dealing with harmful flammable and explosive materials. It is an environmental friendly ink
5. It has strong printing adaptability and can meet the needs of a variety of substrates. Of course, UV curing ink also has some disadvantages: some require NBR cots or EPDM cots, and sometimes special blanket may be required. Blanket may also need special cleaning agent to prevent excessive shrinkage, expansion or quality degradation of blanket. Secondly, its cost is higher than traditional ink. However, the high cost is worth it compared with the final print performance
uv printing and glazing can carry out various value-added printing technologies on various materials, including metal foil and plastic. The growing demand for UV has been developing for many years. The annual growth rate of UV market in the world is nearly three times higher than the average growth rate of the printing industry, and the growth is even stronger in sheet fed printing and many flexographic applications
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