UV curing ink refers to an imaging substance that uses ultraviolet light of different wavelengths and energy to polymerize the monomers in the ink binder into a polymer, which is then cured into a film and dried.

In the process of printing membrane switch panels, we often encounter undesirable phenomena such as insufficient UV ink curing and weak adhesion, which affect the image, color, and clarity of the panel surface. Follow our engineers today to learn about the causes and solutions of common quality problems in UV inks during the printing process.

Common Poor Curing Problems

If the UV ink is not cured completely, the adhesion of the ink layer is relatively poor, which will cause pollution to other products during the printing process. At the same time, the surface of the ink layer is not resistant to friction and is easily scratched during subsequent processing and the use of printed materials, which seriously affects the printing quality.

In the large-area printing process, due to the large amount of ink, the ink cannot be completely dried when the printed matter is dried by the UV lamp. This will lead to the phenomenon that the surface layer of the ink is dried but the bottom layer is not completely dried. We call this phenomenon of false drying of the ink. Especially when printing dark colors, it is easy to produce false dry phenomenon due to the slow curing speed. On the one hand, because white can reflect all visible light and requires higher energy during curing, it is more difficult to cure white ink. On the other hand, although black can absorb all the light in theory, but because of the blocking effect of the ink on the light, it also hinders the deep curing, so the curing speed of dark color inks such as black is slower.

Judgment Methods of Poor Curing

After years of production practice, we have summarized a variety of judgment methods. It can be roughly attributed to the appearance observation method, physical test method and chemical test method.

(1) Appearance observation method

The appearance observation method does not require any external tools, and is directly judged by observing whether the UV ink layer has a bright surface. Generally speaking, the fully cured UV ink ink layer has a bright surface.

(2) Physical testing method

There are two commonly used physical test methods.

Method 1: Lay a piece of paper on the UV ink layer on the surface of the printed matter, press the paper with your hand and rub it on the UV ink layer a few more times. If you find that the UV ink layer on the surface of the printed matter is damaged, then UV The ink layer is not fully cured.

Method 2: Use a pin to scratch the surface of the UV ink layer on the surface of the printed matter, and then place it under a 200x magnifying glass to observe the scratches. If the scratches on the UV ink layer are found to be jagged, it indicates that the UV ink layer has been completely cured.

(3) Chemical testing method

The chemical test method requires the aid of acetone solvent for testing. Drop the acetone solvent on top of the UV ink layer. If you find that the UV ink layer can be dissolved, it means that the UV ink layer has not been completely cured.

Solution to Poor Curing 

The most thorough way to solve the problem of poor curing of UV inks is to switch to UV inks with faster curing speeds. Of course, you can also use a higher color density ink to achieve the desired color reproduction with a thinner ink layer. That is, by thinning the ink layer, the curing efficiency of the ink is improved, and the ink is completely cured.

In some cases, it is not necessary to replace the ink, and the curing efficiency of the UV ink can be improved by adding an appropriate amount of curing aid to achieve the complete curing of the ink layer.