| 摘要 |
<p>Water and oil base ink are delivered to lithographic plates as a single liquid (21), a mixture of water and ink, wherein the water is in the form of fine droplets. Preferably also, lithographic concentrate is added to the mixture as part of the water content. During a printing run the mixture (21) is automatically resupplied to the printing machine by a level sensor (43) that controls the amount of ink and water and by a pH sensor (42) that controls the concentrate percentage. The proportion of ink and water is controlled by a moisture sensor (41). The thickness of the film of mixture delivered to the lithographic plate is controlled by a density sensor (46). A viscosity sensor (44) controls the agitation of the mixture. A set of three rollers (34, 37, 39) is used to deliver the ink-water-concentrate mixture to the lithographic plate (38) in contrast to several dozen rollers conventionally used. The rollers (112) that supply ink and/or water to form rollers (113) have a surface with minutely intermixed hydrophilic and oleophilic areas (140, 141, 151, 152, 161, 162). The amount of water retained by a roller is dependent upon the total of the hydrophilic areas (e.g. 140), and the amount of oil-based ink retained by the roller is dependent upon the total of the oleophilic areas (e.g. 141). A preselected ratio of oil to water is obtained by selecting the ratio of hydrophilic areas (e.g. 140) to oleophilic areas (e.g. 141) </p> |
