Lithographic printing plate having dual photosensitive layering

Claim 1

A lithographic printing plate capable of development with an aqueous alkali developer which comprises a sheet substrate having coated thereon a light-sensitive, lithograhically suitable, water-soluble diazo composition, said diazo composition having coated thereon a lithographically suitable photopolymerizable composition, which photopolymerizable composition comprises the admixture of, in percent by weight of the photopolymerizable composition: (a) an acrylonitrile butadiene styrene resin in an amount of from 2% to 25%; and (b) one or more resins selected from the group consisting of solid acrylic, polyurethane and polyamide resins in an amount of from 4% to 50%; and (c) cellulose acetate phthalate in an amount of from 4% to 50%; and (d) one or more ethylenically unsaturated monomeric or oligomeric compounds having on the average, more than one double bond, and being capable of forming a high polymer by free radical addition photopolymerization, in an amount of from 20% to 60%; and (e) a photoinitiator capable of generating free radicals in an amount of from 0.5% to 45%; and (f) p-phenol sulfonic acid sodium salt in an amount of from 0.4% to 5%.