It is not easy to produce deep black UV -coatings with Pigment Carbon Blacks. The main barrier is the particle size.
In the literature you find formulations including 25nm-Carbon Black Pigment, oxidised and combined with specific high reactive accelerators and selected acrylic resins. That's the limit insofar as blackness concerns. Better colouristic results are obtainable by using Aniline Blacks.
Specialty Carbon Blacks with larger particle sizes which are after-treated, are a good option only for black coatings and UV-curing printing inks.