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首页> 外文会议>Appita Annual Conference and Exhibition incorporating the ISWFPC(International Symposium on Wood, Fibre and Pulping Chemistry) vol.2: 13th ISWFPC Sessions - Oral Papers; 20050516-19; Auckland(NZ) >Behavior of chromophoric structures in softwood TMP during H_2O_2 bleaching
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Behavior of chromophoric structures in softwood TMP during H_2O_2 bleaching

机译：H_2O_2漂白过程中软木TMP中发色结构的行为

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摘要

A commercial TMP and an isolated lignin from the TMP (milled pulp lignin, or MPL) were treated with alkaline H_2O_2 bleaching as well as with several other specially designed chemical reactions. Analyses with NMR indicated that coniferaldehyde structures were eliminated completely from the lignin polymer by H_2O_2 bleaching. Phenolic content was found to have little impact on the final brightness of the TMP sample. Significant amounts of vanillin units (～ 4%) were stable towards alkaline H_2O_2 bleaching and they remained in the TMP lignin after H_2O_2 bleaching. Even though the lignin sample was completely dissolved during the bleaching treatment, full brightness could not be achieved with the alkaline H_2O_2 bleaching treatment alone irrespective of the H_2O_2 charges being used, indicating that physical hindrance was less likely to be an important factor causing the brightness ceiling. It was probably the presence of certain H_2O_2-resistant chromophores in the unbleached TMP that limited the further brightness improvement of the TMP at a certain brightness level. The bulk of the polymeric lignin structure seemed to be stable towards alkaline H_2O_2. The total coniferaldehyde and vanillin units present in the lignin polymer can only account for part of the H_2O_2 consumed (not more than 10 kg/ton) during the bleaching process. The predominant reaction responsible for the consumption of H_2O_2 during the bleaching process was found to be the formation of carboxylic acid groups.
机译：商业TMP和从TMP中分离出的木质素（磨浆木素或MPL）经过碱性H_2O_2漂白以及其他几种特殊设计的化学反应处理。 NMR分析表明，通过H_2O_2漂白从木质素聚合物中完全消除了松柏醛结构。发现酚含量对TMP样品的最终亮度几乎没有影响。大量的香兰素单元（〜4％）对碱性H_2O_2漂白是稳定的，并且在H_2O_2漂白后仍保留在TMP木质素中。即使木质素样品在漂白处理过程中完全溶解，但仅使用碱性H_2O_2漂白处理就无法获得完全的亮度，而与使用的H_2O_2电荷无关，这表明物理障碍不太可能是导致亮度上限的重要因素。未漂白的TMP中可能存在某些耐H_2O_2的发色团，这限制了TMP在一定亮度水平下的进一步亮度改善。大部分聚合物木质素结构似乎对碱性H_2O_2稳定。木质素聚合物中存在的总松柏醛和香兰素单元仅占漂白过程中消耗的H_2O_2的一部分（不超过10千克/吨）。发现在漂白过程中引起H_2O_2消耗的主要反应是羧酸基团的形成。

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