Interpretation of printing and coating process（3）

There are many types of varnishes, but the commonly used varnishes can be roughly divided into three categories: oily varnishes, water-based varnishes and UV varnishes. According to the actual application trend of glazing oil and the improvement of environmental protection requirements, the use of oily glazing will decrease day by day, and the application space of water-based glazing oil and UV glazing oil is very broad. This section mainly introduces water-based glazing oil and UV varnish.

The water-based varnish is mainly composed of water-soluble resin and water-dispersed resin. The water-based varnish is non-toxic and tasteless, eliminating the harm to the human body and pollution to the environment. It has fast drying speed, good film transparency, stable performance, The equipment has the characteristics of wide adaptability, good abrasion resistance and flatness of the glazing surface, wide post-press processing adaptability, good heat sealing performance, safe and reliable use, convenient storage and transportation, etc., and it is more and more popular for food, medicine, tobacco carton packaging. The attention of printing companies.

The following typical problems should be paid attention to when using UV water-based varnish:

1. How to ensure that the underlying ink can be fully dried after applying the water-based varnish. First of all, ensure the air permeability of the water-based varnish so that the wet ink layer can be exposed to air to dry the oxidized conjunctiva. In addition, it can also be properly dried. This problem can be solved by increasing the temperature of the hot air.

2. The gloss of water-based glazing oil is lower than that of UV glazing oil. In practice, a small amount of high-boiling solvent can be added to the water-based glazing oil to moisten and swell the emulsion particles and promote the formation of a smooth coating film. So as to improve the surface flatness of the coating film, and finally achieve the purpose of improving the gloss of the water-based varnish coating.