Due to their different characteristics, water-based ink and UV ink in digital printing have different requirements for the ink supply system, drying or curing system, and key components such as nozzles of the machine. When choosing inks and printing equipment, printing companies need to fully consider these differences to ensure efficient and stable printing production and provide the market with high-quality printing products.
Water-based ink uses water as a solvent and has outstanding environmental performance. It is increasingly favored in the market environment that focuses on green printing. Due to the fluidity and drying characteristics of water-based ink, the ink supply system of the printing machine has high requirements. The viscosity of water-based ink is relatively low, which requires the ink supply system of the machine to have precise control capabilities to ensure that the ink can be stably and evenly delivered to the printing nozzle or roller. If the ink supply is unstable, it is easy to cause uneven light and dark printing patterns. In addition, the drying of water-based ink depends on the volatilization of water, so the printing machine needs to be equipped with an efficient drying system. Usually, a hot air drying device is used to accelerate the evaporation of water by precisely controlling the temperature and wind speed, so that the ink can be dried and fixed quickly. However, excessive temperature may cause paper deformation and affect the accuracy of printing registration, so the temperature control of the drying system must be precise.
UV ink is cured by ultraviolet radiation, and has the advantages of fast drying speed and good ink film performance. Unlike water-based ink, UV ink has strict requirements on the curing system of the machine. UV ink printing machines need to be equipped with professional UV curing lamps, which can emit ultraviolet rays of a specific wavelength to decompose the photo initiator in the ink to produce free radicals, thereby initiating a polymerization reaction and achieving instant curing of the ink. The power, wavelength and distance of the UV curing lamp from the printing material are all crucial. Insufficient power will cause the ink to be fully cured, resulting in the stickiness of the printed surface and easy contamination of dust; inappropriate wavelength will not effectively induce the curing reaction. At the same time, the UV curing process will generate a lot of heat, and the machine must also be equipped with a good heat dissipation device to prevent damage to the printing parts or affect the printing quality due to excessive temperature.
In terms of nozzles, there are also differences in the requirements of water-based inks and UV inks for machine nozzles. The water molecules in water-based inks are corrosive to the nozzle materials, so the nozzles need to be made of corrosion-resistant materials and have a good cleaning and maintenance system to prevent nozzle clogging. Because water-based ink will form dry matter inside the nozzle after drying, affecting the smoothness of ink spraying. UV ink has a fast curing speed, which requires the nozzle to respond quickly to printing instructions and accurately control the ink spraying amount and spraying position. Once the nozzle response speed is slow or the spraying accuracy is poor, when the UV ink is cured quickly, problems such as blurred patterns and unclear lines are likely to occur.
