company news about Application of UVLED technology in printing field

Application of UVLED technology in printing field

  The so-called UV LED technology refers to the special design that enables LED (Light-Emitting Diode) to emit a complete and continuous ultraviolet light band to meet the needs of different fields for ultraviolet light sources. With the continuous development of this technology, many fields such as electronics, printing, and medical care have begun to use this technology. The development of UVLED technology in the printing field is particularly prominent. In just a few years, major well-known printing machine manufacturers have launched UVLED printing machines, and the types of printing machines cover almost all printing methods from screen printing, letterpress label printing, digital inkjet printing, sheet-fed offset printing, etc.

  UV LED curing device is the key technology of the entire UVLED printing system. The main peaks of traditional medium-pressure mercury lamps are at 365nm, 313nm, and 303nm, and the continuous spectrum emits ultraviolet rays from 200nm to 400nm. At present, LEDs only emit ultraviolet rays in a few very narrow bands such as 365nm, 385nm, and 405nm, which limits the scope of use of LEDs. Some foreign researchers are developing LED chips that emit ultraviolet rays in the mid-ultraviolet range. Chips with wavelengths of 247nm and 210nm have been successfully developed. The application of this achievement enables UVLED curing equipment to emit a nearly continuous spectrum at multiple wavelengths, thereby simulating the continuous spectrum emitted by medium-pressure mercury lamps.The design and production of UVLED curing devices need to take into account that LEDs release a lot of heat when working, so a cooling system needs to be installed for them. At present, air cooling and water cooling systems are commonly installed. The curing device of printing equipment is equipped with a water cooling system because it has many modules and a compact structure, which greatly increases the difficulty of designing the curing device.

  UV LED inks are different from ordinary UV inks in terms of spectral characteristics to adapt to their curing devices. They contain many core technologies, the most important of which is the photoinitiator. The photoinitiators generally used in ordinary UV inks have a wide absorption range, as shown in Table 1. When choosing a combination, the competition between the photoinitiator and the pigment for ultraviolet light should be considered. Therefore, the absorption peak of the photoinitiator is best located in the "light transmission window" where the pigment absorbs relatively weak ultraviolet light.However, LED curing devices only emit ultraviolet light of a specific wavelength and a narrow spectrum, which requires LED photoinitiators to have stronger light absorption ability and higher reaction efficiency, and the absorption peak must match the emission wavelength.

  Advantages of UV LED technology compared with traditional UV
1. Lower energy consumption, power consumption is only 10% of traditional mercury lamp curing device;
2. Longer life, equivalent to 10 times the life of traditional mercury lamp;
3. Cold light source is suitable for curing on heat-sensitive substrates such as thermal paper and plastic sheets
4. No preheating process is required, it can be turned on and off directly without affecting the life;
5. It does not release ozone, does not emit UVC, and is more environmentally friendly;