20 classic problems in the use of UV curing ink

1. What happens when the ink solidifies excessively? There is a theory that when the ink surface is irradiated by too much ultraviolet light, it will become harder and harder. When people print an ink on this hardened ink film and dry it for the second time, the adhesion between the upper ink and the lower ink will become very poor. Another theory is that excessive curing will cause photooxidation on the ink surface. The occurrence of photooxidation will destroy the chemical bond on the surface of the ink film. If the molecular bond on the surface of the ink film is degraded or damaged, the adhesion between it and another ink layer will be reduced.

The over cured ink film not only has poor flexibility, but also is prone to surface embrittlement.

2. Why do some UV inks cure faster than other inks? UV ink is generally prepared according to the characteristics of some substrates and the special requirements of some applications. From a chemical point of view, the faster the curing speed of ink, the worse its flexibility after curing. You can imagine that when the ink solidifies, the ink molecules will have cross-linking reaction. If these molecules form many molecular chains and have many forks, the curing speed of the ink will be very fast, but the flexibility is not high; If the molecular chains formed by these molecules are relatively few and there is no bifurcation, the curing speed of this ink may be very slow, but it must be very flexible. Most inks are designed according to application requirements.

For example, for the ink specially designed for the production of film switches, the cured ink film must be compatible with the composite adhesive and be flexible enough to adapt to subsequent processing such as die cutting and embossing.

It is worth noting that the chemical raw materials used in the ink cannot react with the surface of the substrate, otherwise it will cause cracking, fragmentation or delamination. The curing speed of this ink is usually slow. Those inks specially designed for the production of cards or hard plastic display boards do not need to have such high flexibility, and their drying speed is relatively fast according to the needs of applications. Whether the drying speed of ink is fast or slow, we should take the application of Z terminal as the starting point. Another noteworthy problem is the curing equipment. Some inks can be cured quickly, but due to the low efficiency of the curing equipment, the curing speed of the ink may slow down or the curing is incomplete.