UV inks from UV printer have the advantages of faster drying speed and lower VOC content than other UV-curable UV inks. However, on some non-absorbent substrates, UV inks sometimes cause a problem of low adhesion of the ink to the substrate because of the instantaneous drying of the UV ink. Although the degree of adhesion required depends on the end use environment and use of the printed product, the adhesion of the UV ink to the substrate can be improved after a suitable method is employed.
To improve the curing degree of UV ink of UV printer, we can start from the following aspects:
1) Increase the power of the UV curing lamp: On most substrates, increasing the power of UV curing will increase the adhesion of the UV ink to the substrate. The power of the UV lamp of a typical UV flatbed printer has been adjusted in multiple steps. Generally divided into high-grade, mid-range, low-grade, this will solve the curing problem of different materials.
2) Reduce the printing speed: reducing the printing speed while increasing the power of the UV lamp can also improve the adhesion of the UV ink. On UV flatbed inkjet printers, you can also improve printing by unidirectional printing instead of back and forth printing. However, on substrates that are easily curled, warming and slowing down can also cause the substrate to curl.
3) Check if the UV lamp and its accessories are working properly: If the adhesion on the substrate that is relatively easy to adhere is reduced, it is necessary to check whether the UV lamp and its accessories are working properly. All UV curing lamps have a certain effective service life (generally, the service life is about 1000 hours). When the UV curing lamp is used for more than its service life, the electrode is gradually decomposed with the use of the lamp. The deposition, the transparency and the transmission of ultraviolet light are gradually reduced, and the power is greatly reduced. In addition, if the reflector of the UV curing lamp is too dirty, the reflected energy of the UV curing lamp will be lost (reflecting energy can account for about 50% of the power of the entire UV curing lamp), which will also cause the power of the UV curing lamp to drop. .
There are also some printers whose UV curing light power configuration is unreasonable. To avoid poor ink curing due to insufficient power of the UV curing lamp, it is first necessary to ensure that the UV curing lamp operates within an effective service life. For UV curing lamps that have exceeded the service life, they should be replaced in time, and the UV curing lamps should be cleaned regularly to ensure that the reflectors are clean and the loss of reflected energy is reduced.
4) Reduce the thickness of the ink layer of the UV flatbed printer: Since the effect of adhesion is related to the degree of photocuring of the UV ink, reducing the amount of the UV ink will promote adhesion to the substrate. For example, in the large-area printing process, since the ink supply amount is too large, the ink layer is too thick, and when the UV light is cured, the ink surface layer is solidified and the underlayer is not completely cured. Once the ink appears to be dry, the bonding force between the bottom layer of the ink and the surface of the substrate is deteriorated, which may cause the ink layer on the surface of the printed matter to fall off due to surface friction during the processing of the subsequent process. When printing large-area live parts, pay attention to strict control of the amount of ink. For some spot color printing, it is best to adjust the color a little when dispensing ink, so that deep ink can be printed in the printing process, so that the ink is fully cured and the ink layer is strengthened.