ユーカリパルプの道管要素 ＩＩ ユーカリ道管要素の抄紙特性および化学分析値

Abstract

Mechanical and chemical characteristics of eucalyptus vessel elements have beee studied with special reference to their effects on paper qualities. Any significant morphological changes of eucalyptus vessels during beating were not observed down to 440 ml freeness level, indicating that a more intense beating action should be applied to effect vessel breaking. From the paper-sheet forming study in which the separated vessel elements were blended with wood fibers at various vessel ratio ranging from 0 to 100%, it was found that the vessel elements tended to result in higher sheet density, reduced air permeability, lower stiffness, and deteriorated tensile, tear, plybond, and surface strengths. Intrinsic strength of vessel elements, and their inter-element adhesion were found to be considerably lower than those of wood fibers, which seems to be accounted for the greater part of the abovementioned effects.The separated eucalyptus vessel elements were dyed, mixed in paper stock furnish, and formed into paper sheets using a pilot paper machine. The results of this experiment indicated that the transverse distribution of vessel elements in the sheets were rather uniform, and that the vessels which were picked out in a high-tack offset printing corresponded to only a slight portion of total number of surface exposed vessel elements. The apparent density of eucalyptus vessels was calculated as 1.66 by author, which is considered to be considerably higher than that of wood fibers. A chemical analysis of seperated eucalyptus pulp components (wood fibers, parenchyma cells, and vessel elements) revealed that the pentosan content was highest in the vessel elements, whereas the pitch was localized mostly in the parenchyma cells and to a lesser extent in the vessel elements.