Multi-layer negative working imageable element

#The invention relates to imageable elements useful in lithographic printing. More particularly, this invention relates multi-layer, negative working imageable elements useful as lithographic printing plate precursors.

#In lithographic printing, ink receptive regions, known as image areas, are generated on a hydrophilic surface. When the surface is moistened with water and ink is applied, the hydrophilic regions retain the water and repel the ink, and the ink receptive regions accept the ink and repel the water. The ink is transferred to the surface of a material upon which the image is to be reproduced. Typically, the ink is first transferred to an intermediate blanket, which in turn transfers the ink to the surface of the material upon which the image is to be reproduced.

#Imageable elements useful as lithographic printing plates, also called printing plate precursors, typically comprise an imageable layer applied over the surface of a hydrophilic substrate. The imageable layer includes one or more radiation-sensitive components, which may be dispersed in a suitable binder. Alternatively, the radiation-sensitive component can also be the binder material.

#In the Examples, “coating solution” refers to the mixture of solvent or solvents and additives coated, even though some of the additives may be in suspension rather than in solution, and “total solids” refers to the total amount of nonvolatile material in the coating solution even though some of the additives may be nonvolatile liquids at ambient temperature. The indicated percentages are percentages by weight based on the total solids in the coating solution.

#Blue Dye B Simbase Victoria Blue FBO 23363 (Charkit, Darien Conn., USA)

#Blue Pigment A 13.8% solids dispersion of resin B with Irgalith Blau GLG (copper phthalocyanine) (96.9%) in 1-methoxypropan-ol (86.2%) (Eckart Zulch, Germany)