Urethane acrylate — commonly called PU-acrylate — exists to solve the brittleness problem in UV coatings. The polyurethane segment contributes toughness, elongation and adhesion; the acrylate end groups contribute the fast radical cure that makes UV worth using.
It is the correct choice wherever the coated part has to flex: packaging films, flexible substrates, parts that are formed after coating. A conventional hard UV coating cracks in those applications; a urethane acrylate does not.
Aliphatic versus aromatic is the first selection decision. Aliphatic urethane acrylates resist yellowing and are used where colour stability matters — clear coats, whites, light-exposed surfaces. Aromatic versions cost less and cure well but yellow over time, which is acceptable in pigmented or non-critical work.