Adhesion to UV-Curable Powder Coat

Question:

I am a printing shop supervisor searching for a UV ink which can be printed on a metal substrate powder coated with a polyester. Is there such an animal? Would a UV ink stick to a UV powder coat? C.N.

Answer:

First, I must tell you that I am a paint expert not an ink expert. Having said that, I really see no great differences between most materials used in the coatings and printing industries; for the most part, the resins and pigments are the same. I realize that the pigment volume concentrations and the additives are different. Since they are different, so are the viscosities. However, the UV-curable resin could be the same for coatings and inks. I usually say the resin doesn’t care if it’s in an ink or a coating. It will still cure when exposed to UV radiation.

With the aforementioned facts in mind, let me answer your questions. Yes, there are UV-curable inks commercially available and they have been for some time. I just read an article on the subject. That’s the good news. The bad news is that I didn’t keep the magazine and can’t give you a reference. Second, UV-curable ink will stick to a UV-curable powder coating. That is provided that the UV-curable powder coating does not contain a slip agent (slip agents are used to improve mar resistance) on the surface. If so, the slip agent would act as an interference coating and nothing would stick to it without some kind of pretreatment.