Packaging offset printing is used by more and more customers due to its high speed, high efficiency, good dot reducibility, strong pattern texture, and wide range of printing capabilities. For some non-absorbable substrates such as aluminum cardboard and plastic sheets, the offset printing is generally a UV printing process. Because UV offset printing has the following advantages over traditional offset printing:
1. Fast curing
Ordinary offset printing takes several hours or more to fully dry the ink and go to the next processing step. UV offset printing can be completely cured in 1 second to several seconds, so it is especially suitable for printing some non-absorbent substrates.
2. Strong wear resistance
After the UV ink is cured and formed into a film, the friction resistance thereof is good, and the loss caused by the friction during the use and transportation of the packaging product is reduced.
3. Green printing
UV inks do not contain solvents, there is no evaporation of solvents, will not cause pollution to the atmosphere, are green printing.
4. Powder free
Because the ultraviolet rays can be solidified and dried in time, no dusting is required, which greatly improves the working environment. At the same time, it is also conducive to post-press processing, such as laminating and polishing.
5. High efficiency and good quality
UV offset printing production cycle is short, the production capacity is high, and the printing outlets are clear and of good quality. However, because the UV offset printing process is more complex and the application time is not long, it needs to be continuously summarized in the application of the printing process. To see the deficiencies in UV offset printing, continuous improvements are made. I would like to talk about my own opinion on the issues that should be noted in packaging UV offset printing:
1. UV curing device
Since the curing of the UV ink is based on absorption of ultraviolet light by the photoinitiator, polymerization and cross-linking reaction of the monomer and the prepolymer are initiated to cause curing. So offset UV must install UV lamp. General offset presses need to install 3 to 6 UV lamps and exhaust pipes. UV UV lamps must use suitable wavelengths, typically in the range of 200 to 450 nm, and control the distance from the illuminated surface. Also have a spotlight cover. Under the same lamp tube, the efficiency of the lampshade will be very different. Under the irradiation of ultraviolet light, ozone is generated in the air, so ventilators such as exhaust pipes are required. After a certain period of time, the UV lamp will age and its energy will be reduced. Its service life is generally around 1000 hours. Therefore, in the usual printing, attention should be paid to the UV lamp's spotlight, and dust must be wiped clean. The use of UV lamps should also be remembered. More than the use of time should always pay attention to the detection of UV ink curing fastness, in order to replace the UV lamp. UV light has some damage to the human body, so it is necessary to take measures to block light.
2. Use of UV ink
Some components of UV inks come into contact with human skin to produce certain irritating effects and may even cause skin allergic reactions. Therefore, avoid skin contact with ink during use, such as wearing gloves or washing hands frequently. UV inks and ordinary inks If you exchange printing on one machine, then we must clean the ink roller and ink fountain. If the ordinary ink is not clean, it will affect the curing and drying of the UV ink. The auxiliary material of the ink cannot be used casually, and it is necessary to use a dedicated auxiliary material that matches the UV ink.
3. Adhesion
Plastic sheets, aluminum foil and other substrates have poor permeability and weak ink adsorption. In order to improve the adhesion of UV inks to these non-absorbent materials, UV offset printing requires the surface energy of the substrate to be 40 dyn or more.
1. Fast curing
Ordinary offset printing takes several hours or more to fully dry the ink and go to the next processing step. UV offset printing can be completely cured in 1 second to several seconds, so it is especially suitable for printing some non-absorbent substrates.
2. Strong wear resistance
After the UV ink is cured and formed into a film, the friction resistance thereof is good, and the loss caused by the friction during the use and transportation of the packaging product is reduced.
3. Green printing
UV inks do not contain solvents, there is no evaporation of solvents, will not cause pollution to the atmosphere, are green printing.
4. Powder free
Because the ultraviolet rays can be solidified and dried in time, no dusting is required, which greatly improves the working environment. At the same time, it is also conducive to post-press processing, such as laminating and polishing.
5. High efficiency and good quality
UV offset printing production cycle is short, the production capacity is high, and the printing outlets are clear and of good quality. However, because the UV offset printing process is more complex and the application time is not long, it needs to be continuously summarized in the application of the printing process. To see the deficiencies in UV offset printing, continuous improvements are made. I would like to talk about my own opinion on the issues that should be noted in packaging UV offset printing:
1. UV curing device
Since the curing of the UV ink is based on absorption of ultraviolet light by the photoinitiator, polymerization and cross-linking reaction of the monomer and the prepolymer are initiated to cause curing. So offset UV must install UV lamp. General offset presses need to install 3 to 6 UV lamps and exhaust pipes. UV UV lamps must use suitable wavelengths, typically in the range of 200 to 450 nm, and control the distance from the illuminated surface. Also have a spotlight cover. Under the same lamp tube, the efficiency of the lampshade will be very different. Under the irradiation of ultraviolet light, ozone is generated in the air, so ventilators such as exhaust pipes are required. After a certain period of time, the UV lamp will age and its energy will be reduced. Its service life is generally around 1000 hours. Therefore, in the usual printing, attention should be paid to the UV lamp's spotlight, and dust must be wiped clean. The use of UV lamps should also be remembered. More than the use of time should always pay attention to the detection of UV ink curing fastness, in order to replace the UV lamp. UV light has some damage to the human body, so it is necessary to take measures to block light.
2. Use of UV ink
Some components of UV inks come into contact with human skin to produce certain irritating effects and may even cause skin allergic reactions. Therefore, avoid skin contact with ink during use, such as wearing gloves or washing hands frequently. UV inks and ordinary inks If you exchange printing on one machine, then we must clean the ink roller and ink fountain. If the ordinary ink is not clean, it will affect the curing and drying of the UV ink. The auxiliary material of the ink cannot be used casually, and it is necessary to use a dedicated auxiliary material that matches the UV ink.
3. Adhesion
Plastic sheets, aluminum foil and other substrates have poor permeability and weak ink adsorption. In order to improve the adhesion of UV inks to these non-absorbent materials, UV offset printing requires the surface energy of the substrate to be 40 dyn or more.
Ningbo Vinny International Trading Co., Ltd , http://www.vinnystationery.com