熱分解ガスクロマトグラフィーによるリグニン構造解析 （第５報） 機械パルプおよび紙中リグニンの分析

Abstract

Pyrolysis-gas chromatography (Py-GC) is expected to be one of the useful methods for clarifying structural characteristics of lignin in mechanical pulps. In the structural analysis by Py-GC, lignin can be analyzed without being isolated from pulps. Papers which contain mechanical pulps are expected to be characterized by Py-GC. In this report, Py-GC was applied to the characterization of lignin in thermomechanical pulps (TMP) of softwoods and various kinds of papers.Six species : akamatsu (Pinus densiflora), ezomatsu (Picea jezoensis), karamatsu (Larix kaempferi), spruce (Picea sp.), Douglas-fir (Pseudotsuga menziesii), todomatsu (Abies sachalinensis), which were used as raw materials of mechanical pulps, were analyzed by Py-GC. The eight main lignin-derived pyrolysis products (guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, trans-isoeugenol, dihydroconiferyl alcohol, coniferaldehyde and trans-coniferyl alcohol) were detected. Comparing the pyrolysis products of woods, different yields of trans-coniferyl alcohol between the species were observed. Spruce and Douglas-fir showed high yields of trans-coniferyl alcohol, whereas akamatsu and todomatsu did low yields.Py-GC was applied to the characterization of lignin in seventeen kinds of papers : printing and writing papers (wood containing paper, woodfree paper, and wood containing coated paper). Some pyrolysis products from lignin were detected in the analysis of several papers including mechanical pulp. Their characteristics of pyrogram suggested those of the mechanical pulp. Py-GC is more useful than other methods such as alkaline nitrobenzene oxidation because it provides more information on degradation products than alkaline nitrobenzene oxidation. Py-GC was found to be unaffected by filler in paper, while filler usually interfered with exact measurement of the Klason lignin. A kind of paper including hardwood mechanical pulp was clearly distinguished from the others by the detection of syringyl type pyrolysis products. It was considered that the higher yields of the pyrolysis products by Py-GC and the aldehydes by alkaline nitrobenzene oxidation showed the presence of mechanical pulps in papers in higher ratio. When a pyrogram of mechanical pulp is known, it seems to be able to distinguish the paper including the pulp from the others.