POSITIVE-WORKING LITHOGRAPHIC PRINTING PLATE PRECURSORS

摘要

A positive-working lithographic printing plate precursor has an outermost imageable layer that is present at a dry coverage weight of at least 0.7 g/m2 and up to and including 1.6 g/m2 and comprises a primary polymeric binder comprising recurring units of a hydroxyaryl acetal or a hydroxyaryl ester, or recurring units of both a hydroxyaryl acetal and a hydroxyaryl ester. The outermost imageable layer also contains an alkali-soluble secondary vinyl polymer that is not a primary polymeric binder and a non-polymeric polyhydric phenol. These precursors comprise an infrared radiation absorber to make them sensitive and imageable using infrared radiation. After imaging, the precursors can be processed (developed) using an relatively low pH developer such as a silicate- or metasilicate-free developer.