【作者】 沈葵忠；

【导师】 房桂干；

【作者基本信息】 中国林业科学研究院 ， 林产化学加工工程， 2008， 博士

【摘要】 我国造纸工业纤维原料供应短缺,扩大原料供应品种,有利于我国造纸工业的健康发展和生态环境的保护。目前杉木CTMP漂白存在漂白困难、化学药品消耗高、纸浆存在黄颜色底色等问题,其解决可扩大我国造纸工业的原料供应途径,具有重大意义。本论文以我国南方大量种植的杉木为研究原料,以杉木CTMP浆高白度漂白技术及机理为研究课题,研究了机械浆漂白过程中过氧化氢的分解行为及抑制措施,杉木CTMP高温快速漂白,氧化活化改善过氧化氢漂白性能,过氧化物-TAED活化体系漂白,组合漂白中FAS的漂白性能,多段组合高白度漂白技术及漂白性能;探讨了杉木机械浆的可漂白性能及突破其浆料漂白白度增限的方法。在上面研究的基础上,重点探讨了杉木CTMP浆料漂白过程中的木质素结构和功能基团的变化,使用浆料红外光谱、UV-Vis光谱、和Raman激光光谱对漂白过程中的木质素发色基团的脱除机理进行了剖析,提出了一套杉木CTMP纸浆高白度漂白技术。通过对杉木CTMP单段过氧化氢漂白工艺进行优化,提高了杉木CTMP漂白白度增限。优化后的工艺条件是:H₂O₂6%,NaOH用量为4.5%,Na₂SiO₃2%,DTPA0.1%,漂白浓度20%,温度70,时间180min。可以把原浆白度为45.6%ISO的杉木CTMP漂白至79.7%ISO。使用高温短时间漂白工艺（95oC,60min）,能够漂白至77.9%ISO。使用氧化型漂白剂在漂白前进行活化预处理,可以提高后续过氧化氢漂白的效率。几种预处理方式中,以酸性条件下ClO₂活化预处理效果最好,其次是酸性过氧化氢,不加漂白稳定剂的碱性过氧化氢活化效果不够理想。碱性条件下使用的次氯酸盐不适宜做漂白前活化处理剂。使用酸性ClO₂活化预处理（ClO₂用量0.5%,浓度10%,温度70oC,时间30min,用硫酸控制初始pH值4-4.5,终点pH5-6）,经过6%H₂O₂漂白,白度可以达到77.7%ISO,比相同漂白用量（6.5%）的过氧化氢漂白白度增加1.2百分点。对三种过氧化物-TAED活化体系漂白进行了研究比较。机械浆过氧化物-TAED活化体系漂白反应,可以在短时间内完成,漂白时间可以缩短到30 min 60min。H₂O₂-TAED活化体系漂白,温度70oC、时间60min、H₂O₂用量6%、TAED与H₂O₂摩尔比0.1,可实现29.3%的白度增值。FAS漂白应用于杉木CTMP组合漂白可以改善漂白效率,提高白度增限。FAS在两段漂白组合中的位置影响其漂白效果。PF比FP漂白白度约高1²个白度点。FAS漂白可进行高温短时间漂白（90oC、30min）,实现良好的漂白效果。采用FAS还原型漂白作结束段的漂白组合可以取得较好的漂白效果。在10%的总漂剂用量下,使用P*PF漂序浆料白度可以达到83.2%ISO的高白度,且漂白得率损失小。紫外光老化和热湿返黄试验结果表明,以还原型漂白结束的三段组合漂白的白度稳定性良好。机械浆漂白过程对纤维质量产生积极影响。漂白前后,纤维长度和宽度变化不大;但浆料纤维的卷曲和扭结程度有所改善。漂白是机械浆消潜操作的继续,可以改善纸张的抄造性能,提高纸页的强度性能。杉木木质素是G型木质素,存在微量的H型结构;杉木CTMP木质素结构中存在如下官能团:甲氧基;羰基;酚型羟基、非酚型羟基（并以非酚型羟基为主）;对位醌型结构。纸浆的红外光谱分析表明, H₂O₂漂白过程对α和β-羰基都有破坏作用;H₂O₂漂白对木质素苯环结构有破坏作用,能使木质素中苯基丙烷部分分解;未醚化的酚单元更易被破坏和溶出。FAS漂白酚羟基的移除作用不大。纸浆的UV-Vis差谱分析表明,P-TAED活化体系漂白可以移除与苯环相连的共轭羰基发色基团;FAS漂白不仅能够移除与苯环共轭的羰基发色基团,还有效移除浆料木质素中的醌型发色结构;发现FAS漂白置于过氧化氢主漂白段之后可以更好地降低浆料的吸收强度,说明FAS漂白更适宜作为漂白结束段使用。纸浆的Raman光谱分析表明,漂白明显降低松柏醛的结构,进而改善浆料的稳定性能。研究提出了漂白过程中FAS与木质素主要发色结构发生的化学反应的化学式。多段漂序结束段的FAS漂白,能够把木质素中的主要发色基团（α-羰基和醌型结构）还原为羟基,起到纸浆脱色和漂白作用。随着FAS和TAED销售价格的降低,三段组合漂白工艺P*PF有望在工业上得到推广应用。更多还原

【Abstract】 China’s paper industry is facing the pressure of fiberous-materials supply , which have great drawback impacts on the country’s paper industry. Therefore, the central government of China has issued sets of policies and regulations to encourage development of fast-growing wood plantations and improvement of untilization efficiency of woods and efforts of exploring new pulp wood resources as well. In the southern part of China, China fir （ Cunninghamia lanceolata ） has been used as raw materials in pulp mill for kraft pulping and chemimechanical pulping. CTMP pulp from this kind of fir has a difficulty in being bleached for higher brightness level with an economical chemicals application amount, which impacts on the application of those pulps in some high-quality paper and paperboard grades.The following aspects of topics have be investigated by this thesis, including hydrogen peroxide degraduation behaviors and its inhabitation measures; new bleaching process at high temperature and reducing retention time; enhancement pulps’bleachabilities by oxidant activation of unbleached pulps; investigations on combination of bleaching chemical mixtures, such as peroxides-TAED; and applications of some new bleaching chemicals as FAS as well; the order of bleaching sequences for multi-stage bleaching were examined by testing the brightness gains of bleached pulps after those sequences, either.The mechanism for bleaching chemistry have been inspected and proposed, by characterization of lignin-structures of both unbleached and bleached pulp samples. All analytical events are carried out by means of modern instruments i.e. IR spectrometer, UV-Vis spectrometer, UV-confocal resonance spectrometer. The results can indicate the obvious changing of chromophores in bleached pulps. Basing on previous investigations, a proposed suitable bleaching sequence was recommended for high-brightness-bleaching of the fir CTMP pulp.The brightness ceiling of the fir CTMP pulps could be increased after bleaching with optimal conditions of single-stage hydrogen peroxide bleaching, i.e. chemical dosages as H₂O₂ 6%, NaOH 4.5%, Na₂SiO₃ 2%, DTPA 0.1%, and pulp consistency at 20%, temperature at 70oC, retention time for 180 min. The target brightness of bleached CTMP puls can be achieved as 79.7%ISO from the start-point of 45.6%ISO.Improvement of bleaching efficiency has been recognized by oxidant acitivation of unbleached pulp prior to bleaching operation. Comparing the effects on bleaching efficiency enhancement of several types of oxidants, the ascent order could be lined as ClO₂ > acidic H₂O₂ >alkaline H₂O₂ > NaClO. The brightness, 77.7%ISO, of bleached pulps could be achieved after activation by oxidant ClO₂ and one-stage hydrogen peroxide bleaching with a H₂O₂ dosage of 6%; in contrast, if the activation was excutivated by alkaline hydrogen peroxide, the taget brightness of bleached pulp was 76.5%ISO even using a higher H₂O₂ dosage level of 6.5%. Furthermore, the chlorine dioxide activation conditions were used for above trials, which were detailed as ClO₂ dosage of 0.5%, pulp consistency of 10%, reaction temperature at 70 oC, retention time for 30 min. with an initial pH of 4-4.5, at the end of activation reaction, the pH of stocks was adjusted to pH5-6 using 2N H₂SO₄ solution.The brightness values of three bleached pulps were compared after one-stage bleaching with different bleaching chemicals such as alkaline hydrogen peroxide, sodium perborate, sodium percarbonate, and mixed with activator TAED respectively, and the pulps with an initial brightness of 43.8%ISO were used for above trials, and target brightness of all above bleached pulps were 73.1 % ISO, 70.9% ISO and 69.8% ISO, respectively. As the result of TAED application, rentention time of bleaching could be shortened in contrast with a conventional alkalie hydrogen peroxide bleaching.The bleached pulp brightness can be improved with combination of different type chemicals as bleaching agent for their own stage. For instance, oxidizing bleaching （ P ） stage + reducing bleaching（ F or T ） stage as bleaching sequence could provide bleached pulps with brightness of 78%ISO - 80.5%ISO. With comparison of target brightness after PF and FP bleaching, the result shows that, PF sequence does better than FP on brightness ceiling with 1-2 percentage units higher. FAS could also be in high temperature bleaching （90oC, 30min）. A China fir CTMP pulp could be bleached to a brightness of 83.2%ISO by using the three-stage quences of P*PF, with a smaller bleached pulp yield loss and better stabilities, in terms of P.C. Fiber quality index, fiber curl and kink, could be improved by bleaching operations, with little changes in fiber length and wideness. Bleaching operations might move more fiber latencies, which could to lead to improve sheets forming and increase the pulp physical strength properties.China fir lignin is one of G structure type with a ceartain amount of H lignin structures. The following function groups were existed in China fir lignin—carbonyl group, methoxyl group, phenolic and non phenolic hydroxyl group （with non-phenolic being its main components）, quinones structures.Interpreted by IR spectroscopy,α- andβ- carbonyl group in lignin could be destroyed by hydrogen peroxide bleaching, and also phenyl ring. The phenolic groups not etherifying by could be destroyed and removed easily. The phenolic groups were availably removed by FAS bleaching. Interpreted by UV-Vis spectroscopy, the chromophores of carbonyl groups conjugating with phenyl ring might be removed by P-TAED bleaching. And it might be removed by FAS bleachin as well, and also quinines structures. The absorption bands in UV-Vis spectrum were decreased greatly by PF bleaching, which said that FAS was suitable used in end bleaching stage. Interpreted by UV CRS spectroscopy, coniferaldehydes structures might be removed by bleaching, and the pulp bleaching stabilities be further improved.The probable reactions between the two main chromophores groups,α-carbonyl group and o-quinones, in the lignin structures of China fir and the reducing bleaching agent of FAS, were suggested in this paper.With the falling of market sale prices of FAS and TAED in future, it would become a promising bleaching technology of the combining three-stage sequences of P*PF.更多还原