Application of UV ink

Adding luminescent powder to ink is a common method for preparing luminescent ink. In the past, thermosetting ink was mixed with luminescent powder to prepare luminescent ink. With the development of UV technology, the combination of luminescent powder and UV ink to prepare UV luminescent ink has gradually been adopted by a large number of printing manufacturers, especially in the production of luminescent signs, using UV luminescent ink instead of thermosetting luminescent ink has significant advantages. The use of screen printing technology for printing UV luminescent ink is a common method for preparing luminescent signs.
Luminous powder selection
UV luminescent ink should consider the selection of luminescent powder in screen printing, and the basic requirements for luminescent powder are high brightness and moderate particle size. The large particle size cannot leak out of the screen, and the small particle size does not have enough printing thickness. It is necessary to increase the printing frequency to meet the thickness requirements, which wastes time. It is more suitable to use 50-80 μ m luminescent powder. Rare earth luminescent powder is light yellow green, so it is advisable to choose blue or green as the substrate for making signage.
Screen production
Luminous signs generally require a thick printing of the luminous layer, so an 80 mesh polyester monofilament screen is usually used. This allows the luminous powder to pass through the screen, and the printed luminous layer is also relatively thick. In plate making, it is necessary to consider that in general signage products, such as some place name signs, the same pattern is often not printed multiple times in a row. In this case, low-grade oil resistant photosensitive adhesive can be used to save costs.
Pre coated bottom layer
Before printing the luminescent layer, a white bottom layer needs to be printed, and the luminescent layer should be printed on top of the white bottom layer. The bottom layer is one of the necessary steps for printing luminescent ink. Pre coating the bottom layer on the surface of the substrate will help improve the luminescent performance of the coating. The experimental results show that the use of different pigments in the primer has different effects on the luminescence performance of the coating. Adding titanium dioxide to the white primer is most beneficial for improving the luminescence performance of the coating. This is because the white coating can reflect the incident light and emitted fluorescence that pass through the coating more fully, maximizing the effect of the fluorescent coating.
It should be noted that UV luminescent ink needs to have good adhesion on the white substrate, otherwise the luminescent layer will easily peel off after curing. Generally, ordinary PVC ink is used because most UV inks have good adhesion on PVC, which can avoid the phenomenon of the luminescent layer peeling off from the label.
Curing Method
The production process of thermosetting ink is to print the first color (usually dark color first) → send it to an efficient infrared or far-infrared drying machine (conveyor belt type drying channel) for surface drying → print the second color (color sequence usually from deep to light) → send it to an efficient infrared or far-infrared drying machine for surface drying → print the nth color → send it to an efficient infrared or far-infrared drying machine for surface drying n times → finally, the base color is filled and leveled (finishing color) → send it to an efficient infrared or far-infrared drying machine for surface drying → send it to an infrared or far-infrared drying oven for thorough curing and drying. From this, it can be seen that the curing process is cumbersome and consumes a lot of energy. However, using UV ink can be cured instantly after printing through a UV curing machine, and the cured product can immediately proceed to the next process. The process is simple and greatly saves time.