A LITHOGRAPHIC PRINTING PLATE PRECURSOR

摘要

A lithographic printing plate precursor comprising a support having a hydrophilic surface or which is provided with a hydrophilic layer, and a coating thereon, said coating comprising an IR absorbing agent and a polyvinylacetal binder, said polyvinylacetal comprising an acetal group having an acetal carbon atom substituted by a phenolic group, a naphtol group or an antracenol group, a second recurring unit comprising an acetal group having an acetal carbon atom substituted by an alkyl group having a hydrocarbon chain containing 1, 2 or 3 carbon atoms, and a third recurring unit comprising an acetal group having an acetal carbon atom substituted by an alkyl group having a hydrocarbon chain containing 1, 2 or 3 carbon atoms wherein the alkyl group of the acetal group of the third recurring unit is different from the alkyl group of the acetal group of the second recurring unit. The precursor exhibits an improved sensitivity on exposure and the stability against daylight exposure is further improved.