The thickness of the ink layer directly affects the speed of light curing. The thinner the ink layer, the faster the curing speed, and the thicker the ink layer, the slower the light curing speed. This is because the pigments on the surface of the ink absorb some ultraviolet rays, reducing their transmittance through the ink and slowing down the curing reaction. In addition, once the ink is exposed to ultraviolet light, its surface will solidify into a glossy film, which will also hinder the penetration of light and slow down the solidification of the underlying layer.
In packaging printing, to obtain solid and vivid colors, it is often necessary to reprint the same color multiple times, resulting in a relatively thick ink layer. Timely individual printing and curing of each color is crucial for maintaining quality.
However, if the ink is completely cured during the initial printing process, a smooth surface will be formed, which will hinder the adhesion of ink in subsequent overprinting. Ink only stays on the surface rather than sticking, leading to potential adhesion issues. The control of light intensity is crucial: firstly, avoid strong light, and in the final printing stage, increase the intensity by reducing the passing speed. This ensures that ultraviolet rays have sufficient energy to penetrate multiple layers of ink, ensuring complete curing.
In summary, due to the challenges of measuring the degree of ink layer curing and the risk of ink layer delamination, the use of high-quality flexible LED-UV curing ink should minimize overprinting to the greatest extent possible.
Related product recommendation