Main reasons: UV power is not enough; UV lamp aging, strength weakening; Improper selection of UV varnish initiator; Alcohol, toluene and other solvents added too much; Machine paper speed is too fast; Poor light solid performance of UV curable varnish

Solution: timely maintenance of equipment and replacement of lamp; Adding a certain amount of photoinitiator and photosensitizer, such as ternary amine, to speed up the light solid speed; Adjust printing process.