Presensitized lithographic light-sensitive sheet construction

Claim 1

A PRESENSITIZED LITHOGRAPHIC SHEET COMPRISING A BASE SHEET, A SOLUBLE LIGHT-SENSITIVE DIAZO RESIN SENSITIZER LAYER OVERLYING AT LEAST ONE SURFACE OF SAID SHEET IN CONTACT THEREWITH, AND OVER AND IN DIRECT CONTACT WITH SAID SENSITIZER LAYER A THIN CONTIOUS HARD DURABLE ABRASIONRESISTANT AND WEAR-RESISTANT COATING COMPOSED PREDOMINANTLY OF AN ORGANOPHILIC HYDROPHOBIC WATER-INSOLUBLE SOLVENT-SOFTENABLE RESINOUS POLYMER, SAID COATING HAVING A THICKNESS OF AT LEAST ABOUT 0.001 MIL AND CONTAINING NOT MORE THAN ABOUT 50 PERCENT BY WEIGH T OF PIGMENT; SAID SENSITIZER LAYER UPON EXPOSURE OF THE SHEET TO ACTINIC LIGHT THROUGH A TRANSPARENCY REACTING IN THE EXPOSED AREAS AND BECOMING INSOLUBILIZED AND FIRMLY BONDED TO SAID SURFACE OF SAID BASE SHEET; SAID ABRASION-RESISTANT AND WEAR-RESISTANT COATING BEING ISOLATED FROM BONDING CONTACT WITH SAID BASE SHEET AND BEING INTIMATELY ASSOCIATED WITH AND ADHERENTLY BONDED TO SAID SENSITIZER LAYER, AND FURTHER REMAINING ABRASION-RESISTANT AND WATER-INSOLUBLE UPON SUBJECTION THEREOF TO THE PRODUCTS EVOLVED BY SAID SENSITIZER UPON EXPOSURE OF SAID SHEET TO ACTINIC LIGHT, AND BEING FIRMLY BONDED IN SAID EXPOSED AREAS, WHILE BEING READILY REMOVABLE WITH UNEXPOSED SENSITIZER IN AREAS NOT LIGHT-EXPOSED.