Process and apparatus for preparing pigment flush in response to a material property value

Abstract

The present invention provides a process for continuous production of pigment flushes and an apparatus for carrying out the process. In the process of the invention, the pigment press cake is first fluidized. The fluidized press cake and a hydrophobic liquid organic medium are fed into a twin screw extruder. The kneading of the organic medium and press cake between the twin screws flushes the pigment into the organic medium. The water phase and flushed pigment phase are separated by removing at least part of the water phase through a vent in the extruder. An impediment to the flow of material downstream of the water vent causes the flush to accumulate in the vented section for a period of time sufficient to remove the desired amount of the water phase. The flush works over the impediment and passes downstream to where vacuum is applied to remove residual water from the flush. The flush may be further combined with other ink ingredients to form an ink product. The extruder includes at least one monitoring apparatus that continually monitors a property of the material being processed in the extruder and adjusts a process parameter in response to a deviation of the value obtained for the property from a predetermined desired value for the property.