Abstract: A method of lithographic plate making is disclosed wherein a plate precursor is exposed to laser radiation in the wavelength range from 350 to 450 nm, said plate precursor comprising a hydrophilic support and a photopolymerizable or photocrosslinkable image recording layer, and then processed on-press by supplying fountain and ink. The exposure produces a visible image having a 1976 CIELAB color distance ?E between exposed and non-exposed areas of at least 2.5.

Abstract: A method of lithographic plate making is disclosed wherein a plate precursor is exposed to laser radiation in the wavelength range from 350 to 450 nm, said plate precursor comprising a hydrophilic support and a photopolymerizable or photocrosslinkable image recording layer, and then processed on-press by supplying fountain and ink. The exposure produces a visible image having a 1976 CIELAB color distance AF between exposed and non-exposed areas of at least 2.5.

Abstract: A method for preparing a negative-working lithographic printing plate is provided which comprises the steps of (1) providing a lithographic printing plate precursor comprising on a grained and anodized aluminum support, having a hydrophilic surface, a coating comprising (i) polymer particles which are core-shell particles having a hydrophobic heat-softenable core and a hydrophilic shell and (ii) an infrared light absorbing agent, (2) exposing said coating to heat, thereby inducing coalescence of said polymer particles at exposed areas of said coating, and (iii) developing said precursor by applying a gum solution to said coating, thereby removing non-exposed areas of said coating from said support. According to the above method the printing plates exhibit after ageing an improved clean-out and a reduced background stain, resulting in toning-free printing.

Abstract: A method for preparing a negative-working lithographic printing plate is provided which comprises the steps of (1) providing a lithographic printing plate precursor comprising on a grained and anodized aluminum support, having a hydrophilic surface, a coating comprising (i) polymer particles which are core-shell particles having a hydrophobic heat-softenable core and a hydrophilic shell and (ii) an infrared light absorbing agent, (2) exposing said coating to heat, thereby inducing coalescence of said polymer particles at exposed areas of said coating, and (iii) developing said precursor by applying a gum solution to said coating, thereby removing non-exposed areas of said coating from said support. According to the above method the printing plates exhibit after ageing an improved clean-out and a reduced background stain, resulting in toning-free printing.

Abstract: A heat sensitive lithographic printing plate precursor comprising in the order given (i) a lithographic base having a hydrophilic surface, (ii) an image recording layer comprising hydrophobic thermoplastic polymer particles and (iii) a contrast layer, wherein the precursor comprising an infrared absorbing compound present in at least one of said image recording layer or contrast layer and wherein the contrast layer further comprises a colorant capable of providing a visible image after exposure and development of the precursor and wherein the image recording layer is substantially free of the colorant. The printing plate formed after image-wise exposing and processing exhibits an improved image-contrast and reduced staining.