PORE STRUCTURE AND INK-JET PRINTABILITY O F RICE STRAW PULP HANDSHEETS

Pore structures of handsheet made from rice straw pulp were characteri zed by mercury porosimetry. In addition, image qualities in ink jet pr inting were evaluated by using a commercially available ink jet printe r and ail image analyzer. Rice straw pulps were prepared by soda, soda -anthraquinone, and soda-oxygen processes. Silica contents of handshee ts of these sources were found by X-ray fluorescence analysis to be 1. 2%, 1.0% and 13.5%, respectively. The soda-oxygen pulp handsheets had the greatest porosity and the smallest average pore diameters. Particu larly, a considerable number of pores of less than 1 mu m were found i n these sheets. No reduction in the number of micro-pores of less than 0.7 mu m was observed during beating. On the other hand, the soda-ant hraquinone pulping caused no change in the pore volume and porosity of sheets. A better quality image was found in all rice straw pulp hands heets compared with that in softwood bleached kraft pulp (BKP) handshe ets. The handsheets from beaten soda-oxygen pulp had the best dot circ ularity with a smaller variation coefficient of the dot areas. These i mage qualities were found to be closer to those in uncoated ink jet pr inting paper. The larger silica content and the smaller porous structu re in the soda-oxygen handsheet led to the better quality image.