広葉樹ＣＴＭＰの製造 ＩＩＩ ＣＴＭＰ‐Ｏ３プロセスにより製造したパルプの特性評価

Abstract

High yield pulps were produced from hardwoods (birch and oak) by CTMP-O3 process.Chemical and physical properties of these pulps were determined as well as bleachability with alkaline-hydrogen peroxide. Furthermore, changes of the distribution of lignin in the cell wall of the pulps by treatment with ozone and peroxide were observed under a ultraviolet microscope.The yield and lignin content of the ozonized pulps decreased with increasing the rate of ozone consumption.A large portion of dissolved material from the pulps by ozonization was consisted of lignin degradation products. Therefore, it was concluded that lignin reacted with ozone selectively and was almost dissolved from the pulps.The energy required for the second refining, to reach specified freeness, was rapidly decreased by ozonization for 5 min.Sheet strength properties of these ozonized pulps were higher than those of conventional CTMP. Particulary, a remarkable increase in tensile index was found.The transverse sections of the cell wall of ozonized pulps were observed under a ultraviolet microscope at 280 nm. The results showed that lignin was dissolved stepwise from the outermost layer of pulps by ozonization. Elongation of the ozonization time led to the increase of the area of the lignin free region in the cell wall. No differences were found in the mode of delignification between the pulps from birch wood and from oak wood.The PC number of ozonized pulps was significantly decreased by hydrogen peroxide bleaching. The distribution of lignin in the cell wall of the ozonized pulps was changed by the hydrogen peroxide bleaching while this phenomenon was not found for conventional CTMP by hydrogen peroxide bleaching. Lignin remained at the lumen side of the cell wall after ozone treatment found to be dissolved with alkaline-hydrogen peroxide.