Method of improving surface cure in digital flexographic printing plates

A relief image printing element produced from a photocurable printing blank, wherein the photocurable printing blank comprises:

• a) a support layer;
• b) one or more photocurable layers disposed on the support layer, wherein the one or more photocurable layers comprise:
• i) a binder;
• ii) one or more monomers;
• iii) a photoinitiator;
• and
• iv) an additive selected from the group consisting of phosphites, phosphines, thioether amine compounds, and combinations of one or more of the foregoing;
• and
• v) an antioxidant selected from the group consisting of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, alkylated phenols, alkylated bis-phenols, polymerized trimethyldihydroquinone, dilauryl thiopropionate, and combinations of one or more of the foregoing;
• c) a laser ablatable masking layer disposed on the one or more photocurable layers, the laser ablatable masking layer comprising a radiation opaque material;
• and
• d) optionally, a removable coversheet;
• wherein the relief image printing element comprises a plurality of relief printing dots which relief printing dots comprise at least one of the following characteristics;
• (i) edge sharpness of the relief printing dots, defined as the ratio of the radius of curvature re at the intersection of a shoulder and the top of the relief printing dot to the width of the dot's top printing surface p is less than 5%;
• or
• (ii) average shoulder angle, measured as the angle between a shoulder of the dot across the width of the dot's top printing surface, is less than 30°.

A photocurable printing blank comprising:

• a) a support layer;
• b) one or more photocurable layers disposed on the support layer, wherein the one or more photocurable layers comprise:
• i) a binder;
• ii) one or more monomers;
• iii) a photoinitiator;
• and
• iv) an additive, wherein the additive comprises a thioether amine compound, and combinations of one or more of the foregoing;
• c) a laser ablatable masking layer disposed on the one or more photocurable layers, the laser ablatable masking layer comprising a radiation opaque material;
• and
• d) optionally, a removable coversheet,
• wherein the photocurable printing blank is capable of being selectively crosslinked and cured upon exposure to UV light and then developed to reveal a relief image therein, wherein the relief image comprises a plurality of relief printing dots, and
• wherein the presence of the additive in the at least one photocurable layer enhances surface cure of the one or more photocurable layers without requiring a high intensity UV light source, an inert gas chamber, or a laminated membrane.