Hot Stamping on UV Varnish

In printing, UV Varnish has always played the role of high gloss oil. Its unique highlighting effect is recognized by the majority of printing process personnel, but the UV varnish still has deficiencies in many post-processing performances. The following is a brief analysis of the difficulties in hot stamping on the UV lacquer layer from the problems that arise during the development of the test.

(1) To form a high-brightness effect, the UV varnish must have a certain thickness, but the varnish layer is too thick for the hot stamping. Generally, the thickness of the UV varnishes applied by offset printing is above 9g/m2.

(2) In order to ensure the curing performance, special resins and a large amount of additives are needed in the UV varnish, which will inevitably affect the effect of hot stamping on the surface of the UV varnish layer.

(3) At present, the resin component in the UV varnish is not sufficiently good in affinity with the hot stamping foil under high temperature and high pressure, so the hot stamping on the UV varnish layer is not easy to control.

Therefore, the following matters need to be taken into account when hot stamping the surface of the UV oil layer.

(1) When it is necessary to increase the brightness of the UV varnish, the method of increasing the thickness of the varnish layer is not advocated. The flatness and lightening effect of the optical oil layer can be improved by adjusting the coating process parameters (the angle and the number of screen lines of the coating roller, etc.) and the performance of the printing equipment (pressing pressure and printing speed, etc.).

(2) Reasonably select hot stamping materials so that the adhesive layer has a good affinity with the UV varnish resin.

(3) Accurately adjust the temperature and pressure of the hot printing plate because excessive pressure and temperature will destroy the surface properties of the ink and make hot stamping more difficult. At the same time, the hot stamping speed should not be too fast

Because the hot stamping adaptability of UV varnish is not mature enough, the stamping quality is not stable enough. The resin composition and additives of UV varnish are also not conducive to hot stamping. Therefore, we must pay attention to the above aspects.