UV offset printing plates and rollers and drying

The PS plate can be divided into positive plate and negative plate according to the principle of its exposure and imaging. Because the positive part of the positive plate is the photo-curing photosensitive layer, and the blank part, ie the unexposed part, is dissolved away. When cleaning the plate in the process, special cleaning agents are required to clean the plate, and the cleaning power of these cleaning agents is very strong.

In the cleaning process, the photosensitive layer on the graphic part of the plate may be dissolved to cause it to fall off, thereby deteriorating or scrapping the printing plate in terms of ink transfer ability. In order to prevent this problem from occurring, a baking plate treatment is required when the PS positive plate is used. Or use a UV-specific PS plate. The method of baking the plate is to place the plate in a baking oven at a temperature of about 250°C and baking for 6-8 minutes. In this way, the interior of the photosensitive layer of the PS plate can be sufficiently hardened, and at the same time, its abrasion resistance and solvent resistance can be improved.

For the UV printing PS negative version is basically not used, and baking version has no effect.

Printing roller

Due to UV matte film varnish, its connection material contains acrylic resin monomer, photopolymerization initiator and other chemical components, and these components have strong penetration or even dissolution capacity for rubber, which will cause the rubber roller to swell or deform. The change of its transfer ink properties, resulting in a lot of printing failures, so ordinary offset printing ink roller is not suitable for printing UV matte film Varnish. The printing of UV matte film is best to use UV special rubber roller, and sometimes even if the use of UV special roller will also have a variety of problems.

For example, the newly-opened new rubber roller can be used to pre-treat the rubber roller in order to prevent malfunctions when the common ink and the UV matte film are alternately used. For example, it is pre-coated with UV matte film varnish for 24 hours before printing, cleaned before printing, coated with UV matte film varnish for about 1 hour, and then washed with detergent and then inking.

UV matte film drying

The UV drying method and principle of matt film varnish is different from common ink. It causes photopolymerization of the internal components of the ink to be instantaneously cured and dried by ultraviolet light irradiation. Its drying is different from that of common inks such as evaporation, oxidation and penetration drying. There are many places to pay attention to:

(1) It must be confirmed whether the ink layer is really dry and thorough;

(2) UV matte film light oil drying source;

(3) UV matte film varnishes use additives and cleaning, safety precautions.