Patent ID: 7749683

Claim:
A photopolymer printing plate precursor comprising: a photopolymerizable composition on a support, the photopolymerizable composition comprising: a binder, a polymerizable compound, a sensitizer, a photoinitiator, and a polythiol compound, wherein the composition includes, with respect to its total solid weight, from about 0.01 wt. % to about 5 wt. % of the polythiol compound and the polythiol compound is selected from one of the following formulae (IIIa) or (IIIb): wherein R 8 mutually independent means H or a non-metal atom substituent; A 1 , A 2 mutually independent mean a linear alkyl chain with at most 16 carbon atoms; L 3 , L 4 mutually independent mean linking groups or single bonds; s means an integer from 1 to 100; r means 1, 2, 3 or 4; the product of s times r is at least 2; the thiol groups of formulae (IIIa) or (IIIb) may also be present in their tautomeric thione form; the composition, when coated on a support, has a sensitivity of about 150 μJ/cm 2 or higher; and for polythioles of formula (IIIa), R 8 means hydrogen, methyl, or ethyl; and r means 1, 2, or 3.