過酢酸気相漂白したホロセルロースパルプの強度特性

Abstract

Chlorite hollocellulose pulps (NUHP and LUHP) prepared from Douglas fir and eucalyptus chips at room temperature or 50°C were treated by peracetic acid (PA) bleaching in vapor phase or by multistage (MS) bleaching under the various conditions.The mechanical strength, pentosan contents and density of NBHP or LBHP sheet at equal freeness were measuerd. The viscosity of these pulps in a cupri ethylenediamine solution was also determined.The results obtained are summarized as follows.1.The sheet strength of PA-or MS-bleached NHP increased proportionally with increasing viscosity of those bleached pulps in the range of 3 to 12 cp, and also the strength increased linearly with increasing pentosan contents of the pulps in the range of 2.5 to 4.5%. The similar proportional relationship was observed for both PA-and MS-bleached LHP (viscosity of pulp : 4to 8 cp, pentosan contents;6.0 to 9.0%). On the other hand, a linear relationship between the sheet density and pentosan contents of NBHP or LBHP was found to be observable in the range of 2.4 to 4.0% of pentosan contents in former pulp and in the range of 6.0 to 9.0% of pentosan contents in the latter pulp.2. From the results of sugar analysis and gel filtration of hemicellulose isolated from NBHP or LBHP with 5% KOH, it was revealed that uronic acid-rich or pectin-rich hemicellulose has no effects on the density and mechanical strength of NBHP or LBHP sheet. A decrease of xylan contents in BHP during PA-and MS-bleaching was more rapid than that of other hemicellulose contents.