Label UV glazing process and precautions

Currently, the UV coating process has been commonly used in the label industry to replace the surface coating. The glazing of the sticker is divided into light on a sheet of paper and light on a web according to the processing method. Sheets of light are the same as light on plain paper, and web light is the most commonly used method in the label printing process.

The glazing of the sticker is carried out on a turn labelling machine, ie a layer of UV coating is applied evenly to the surface of the left image immediately after printing. For a flexographic print using a water-based ink, the glazing process is an indispensable step.

The following related matters should be noted in UV polishing operations:

(1) The quality of UV coating must be checked before coating. There are many types of UV Varnish, each type of Varnish has a certain storage period, and there are certain requirements for the storage environment. Therefore, before coating, be sure to check the color and timing of Varnish by small batch test. After the cloth is cured and the matching of the additive, etc., also pay attention to whether the coating oil has contact with the ink layer to react. After passing the test, UV Varnish can be used for batch glazing.

(2) Pay attention to controlling the thickness of the coating oil during the coating operation. The leveling properties of UV varnish are not as good as those of solvent type varnish. If the coating amount is too large, the surface of the varnish will appear streaks, affecting its reflection effect on light. If the coating amount is too large, the coating oil will not be completely cured, and only the surface layer will be cured, resulting in adhesion of the label after rewinding.

(3) Control the viscosity of the varnish and the surface tension. The viscosity of the varnish affects its leveling, curing speed, and surface gloss. According to different papers, adjust the viscosity. While adjusting the viscosity, it is also necessary to pay attention to the change of tension on the surface of the varnish, so that the surface tension of the varnish is less than the tension of the ink layer on the surface of the printed matter, so that the varnish completely wets the varnish surface to avoid occurrence of pinholes. Streak and other quality problems.

(4) Note the relationship between the coating speed, the coating amount, the coating roll pressure, and the curing temperature. The above four factors are mutually constrained, and the relationship between them should be reasonably adjusted according to the wetting and absorption of the varnishes on different paper surfaces.

(5) Regularly check the UV curing device. The ultraviolet lamp in the UV curing device will gradually reduce the effective power with the use of time, and its effective power should be periodically detected. The service life of general UV lamp is 1000 hours. When the usage time is close to 1000 hours, it should be replaced in time.