Compared with other heat-cured UV inks, the UV inks of UV printers have the advantages of fast drying speed and low VOC content. However, on some non-absorbent substrates, because the UV ink dries instantaneously, it sometimes causes the problem of low adhesion of the UV ink to the substrate. Although the degree of adhesion required depends on the final use environment and purpose of the printed product, after a suitable method is adopted, the adhesion of UV ink to the substrate can be improved.
Improving the curing degree of UV printer UV ink 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 the general UV flatbed printer has been adjusted in multiple levels, generally divided into high-end, mid-range, and low-end, so that the curing problem of different materials is solved.
2) Reduce printing speed:
Increasing the power of the UV lamp while reducing the printing speed can also improve the adhesion of UV ink. On UV flatbed inkjet printers, one-way printing (rather than printing back and forth) can also be used to improve the printing effect. However, on substrates that are prone to curling, heating and deceleration can also cause the substrate to curl.
3) Check whether the UV lamp and its accessories of the UV flatbed printer are working properly:
If the adhesion on the substrate that is relatively easy to attach at ordinary times 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 (under normal circumstances, the service life is about 1000 hours). When the use time of the UV curing lamp exceeds its service life, the electrodes gradually decompose as the lamp is used, and the inner wall of the lamp tube Deposition occurs, transparency and ultraviolet light transmittance gradually weaken, and the power will be 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 (the reflected 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 decrease. There are also unreasonable power configurations of the UV curing lamps of some printers. To avoid poor ink curing caused by insufficient power of the UV curing lamp, first of all, it is necessary to ensure that the UV curing lamp is working within the effective service life, and the UV curing lamp that has exceeded the service life should be replaced in time. And regularly clean the UV light curing lamp to ensure that the reflector is clean and reduce the loss of reflected energy.
4) Reduce the thickness of the ink layer of the UV flatbed printer:
Because the adhesion effect is related to the degree of UV ink curing, reducing the amount of UV ink will promote the adhesion to the substrate. For example, in the process of large-area printing, the ink supply is too large and the ink layer is too thick. During UV curing, the surface layer of the ink is cured but the bottom layer is not fully cured. Once the ink has the phenomenon of false drying, the bonding force between the ink bottom layer and the surface of the substrate becomes poor, which will cause the ink layer on the surface of the printed matter to fall off due to surface friction in the subsequent processing process. When printing large-area on-site jobs, pay attention to strictly controlling the amount of ink. For some spot color printing, it is best to adjust the color to a darker color when mixing the ink, so that the deep ink can be thinly printed during the printing process so that the ink is fully cured and the ink layer is firm.
