Mask element precursor and relief image-forming system

A relief image-forming system, comprising:

• (1) an imageable material;
• (2) a relief-forming precursor comprising a UV-sensitive layer;
• and
• (3) a developer in which the UV-sensitive layer is soluble or dispersible, the imageable material consisting essentially of, in order:
• (a) a transparent polymeric carrier sheet;
• (b) a non-ablatable light-to-heat converting (LTHC) layer disposed directly on the transparent polymeric carrier sheet, the LTHC layer having an average dry thickness of at least 1 μm and up to and including 5 μm, and comprising:
• (i) a first infrared radiation absorbing material in an amount of at least 0.1 weight % and up to and including 5 weight %;
• (ii) a thermally crosslinked organic polymeric binder material;
• and
• (iii) non-thermally ablatable particles having an average particle size of at least 0.1 μm and up to and including 20 μm and that are present in an amount of at least 0.2 weight % and up to and including 10 weight %, all weight percentages being based on the total dry weight of the LTHC layer;
• (c) a non-silver halide thermally-ablatable imaging layer (IL) disposed directly on the LTHC layer, the IL comprising a second infrared radiation absorbing material and a UV-light absorbing material dispersed within one or more thermally-ablatable polymeric binder materials;
• and
• the imageable material optionally further comprising (d) a transparent polymeric overcoat layer disposed directly on the IL.