Distributor rollers

#The present application relates to a process for producing a rigid roller, to a rigid roller, and to the use thereof.

#This application is a national stage application of PCT/EP 2010/069046, published as WO 2011/069998, which was filed on Dec. 7, 2010, which claims priority to European Patent Application No. 09178216.9, filed Dec. 7, 2009.

#Offset printing is still the dominating technology among printing methods. It is an indirect printing method employed in newspaper, magazine, catalogue and packaging printing etc. In offset printing, a printing forme, typically a thin aluminum plate, is prepared. It is fastened under tension to a plate cylinder and has contact with inking and damping systems in the printing machine. Lipophilic regions of the printing forme accept printing ink, while hydrophilic regions remain free from ink.

#FIG. 1 shows an inking system with an ink fountain roller 1, a doctor roller 2, distributor rollers 3, transfer rollers 4, and ink forme rollers 5.

#A solution of polyamic acid is applied to a steel core by a thin film spin casting process. The material is heated in a rotating condition, so that a substantial part of the solvent evaporates. This causes the coating composition to remain stable after the end of the rotation. Subsequently, the roller is annealed at up to 250° C. Printing experiments with such a roller provided excellent results.

#In the process according to Example 1, a steel core with a roughness Rz of 15 μm was employed. In a coating with a thickness of 80 μm according to Example 1, an Rz of about 2.2 μm remains on the surface. In a coating with a layer thickness of 30 μm, an Rz of about 5 μm remains, i.e., the roughness of the coating can be adjusted by selecting the coating thickness.