A digital printing process that applies a liquid radiation curable primer containing 20 to 80% of at least one acrylate functional monomer and 20 to 60% of at least one thermoplastic polyurethane polymer onto a surface of a flat web or sheet substrate; cures the primer by UV or EB irradiation to give a dry, tack-free surface; and then uses a digital printing press that uses a liquid-toner-based electrographic imaging process with a press blanket to transfer a printed image from the press blanket to the cured-primer coated substrate. The resulting printed web or sheet may have a dry, tack-free semi-interpenetrating polymer network layer adjacent the printed image.