カリ材（Ｅｕｃａｌｙｐｔｕｓ ｄｉｖｅｒｓｉｃｏｌｏｒ）のアルカリ蒸解性

Abstract

As is well known, pulp yields are closely related with the chemical composition of woods. The authors previously pointed out that sulphate pulp yieldsfrom some eucalyptus woods, which contained substatial amounts of polyphenolic extractives like kino, could be predicted by the fol-lowing equation : pulp yield= (wood - kino index) ×0.50However, Eucalyptus diversicolor (Karri) gave significantly higher values than calculated by the above. This aspect has been investigated more in detail in this study.Six E. diversicolor woods from Manjimup, Western Australia, which were of different ages from 16 to 93 years, each of which involved three specimens from the butt, middle and top portions, Karri mill chips from the same source, eucalyptus chips of mixed species from northern Tasmania and plantation eucalyptus chips of five species from South Africa were used. Teak (Tectonagrandis) wood was also studied, which is known containing anthraquinones.Wood analysis of the above samples were shown in tables and figures, where Karri samples showed high polyphenol contents as well as teak wood.Soda, sulphate and tetrahydroanthraquinone (THAQ) -soda pulping by active alkali addition of 12 and 18% were carried out on each sample. As the results, Karri samples gave lower Kappa numbers at the given polyphenol content or higher carbohydrate yields at the given Kappa number compared with other eucalyptus, especially at the lower alkali addition in soda pulping. For example, the carbohydrate yield for Karri wood at Kappa number 80 in soda pulping by12% active alkali was64% compared with57.3% of E. macarthuri. As a part of polyphenols condensed with lignin and remained in pulp, which could be measured as Kappa number or Klason lignin, the true residual lignin in such a pulp should be lower.In the cases of Karri and teak wood, carbohydrate retention and delignification could not be improved by adding sodium suphide or THAQ. Both species showed similar behaviours in alkaline pulping relevant to the pulp yield and Kappa number.Karri, mixed eucalyptus and teak wood were extracted with methanol or1% NaOH solution and cooked by soda process. Also soda pulping of these species were carried out. It was difficult to confirm theeffects of extractives on pulping in both cases, including teak wood. Detections of anthraquinone in methanol extractives from Karri woods by gel chromatographp followed by paper chromatography and the anthrone reaction after reduction treatments gave no positive result.