Why is the curing speed of UV curing Printing ink so fast? How to ensure a reasonable speed?

Why does UV ink cure faster than other inks? UV inks are generally formulated according to the characteristics of certain substrates and the special requirements of certain applications. From a chemical standpoint, the faster an ink cures, the less flexible it will be once cured. As you can imagine, when the ink is cured, the ink molecules will undergo a cross-linking reaction. If these molecules form a lot of molecular chains and have many forks, the curing speed of the ink will be very fast, but the flexibility is not high; If these molecules form fewer molecular chains and are not branched, the ink may be slow to cure, but it must be very flexible.

Most inks are designed based on application needs. For example, for an ink designed for the production of membrane switches, the cured ink film needs to be compatible with the laminating adhesive and flexible enough to accommodate 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. These inks are generally slow to cure. Those inks designed for the production of cards or rigid plastic displays don’t need to be as flexible and, depending on the application, dry faster.

Whether the ink dries quickly or slowly, we always start with the final application. Another noteworthy issue is 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 also be slowed down, or the curing may not be complete.

So how do you ensure proper curing of UV inks?

Curing of the ink film during the first pass through the curing unit is very important. Proper curing minimizes substrate distortion, overcuring, rewetting and undercuring, and optimizes ink-to-hum or coating-to-coat adhesion.

Screen printing houses need to determine production parameters before production starts. In order to test the curing efficiency of UV ink, we can start printing at the lowest speed allowed by the substrate, and then cure the printed sample. Then, set the power of the curing lamp to the value specified by the ink manufacturer. When dealing with colors that are not easy to cure such as black and white, we can also increase the parameters of the curing lamp appropriately.

After the printed sheet has cooled, we can use the two-way hatching method to measure the adhesion of the ink film. If the sample can pass the test smoothly, the paper can be conveyed at an increased speed of 10 feet per minute, and then printed and tested until the ink film loses its adhesion to the substrate, and the speed of the conveyor belt and curing at this time can be recorded lamp parameters. Then, the speed of the conveyor belt can be reduced by 20-30% according to the characteristics of the ink system or the suggestion of the ink supplier.