【作者】 李佩燚；

【导师】 张美云；

【作者基本信息】 陕西科技大学 ， 制浆造纸工程， 2014， 博士

【摘要】 木材纤维资源短缺是长期以来制约我国造纸行业发展的瓶颈。竹材原料的纤维特性与木材最为接近，且在我国分布广泛，慈竹是最适宜用作造纸原料的竹种之一。DDS置换蒸煮（Digester Diagnosis System）的最大优点是节能、环保。因此，开发慈竹DDS置换蒸煮不仅可解决我国原料短缺的问题，而且符合造纸产业绿色、低碳、环保的发展趋势。本论文以慈竹为原料，采用DDS置换蒸煮和清洁漂白技术，对慈竹DDS置换蒸煮、添加助剂的无硫蒸煮系统的研究，揭示了慈竹的低污染制浆特性；结合慈竹氧脱木素以及无元素氯（ECF）漂白和全无氯（TCF）漂白的研究，构建了慈竹DDS置换蒸煮与纸浆清洁漂白的相关性，揭示了慈竹在制浆不同阶段纤维形态的差异及纤维表面特性的变化。丰富了慈竹清洁制浆的理论体系，并对其生产实际具有指导意义。研究了慈竹化学组成及存放时间对慈竹化学组分的影响。结果显示，慈竹皮和杆中的化学组成有一定差异，皮中灰分、苯-醇抽出物含量高于杆中的含量，用作造纸原料的慈竹脱青1~2个月为宜。研究了预处理工艺对慈竹纤维化学组分及后续蒸煮的影响。确定了氢氧化钠和硫化钠共同预浸渍的预处理技术，通过实验该预处理可以使原料中木素含量降低、综纤维素少量降解。经预处理的慈竹与未预处理的慈竹在相同蒸煮工艺条件下，前者蒸煮成浆的得率下降，但卡伯值降低更为显著，黏度有所降低，均能达到可漂浆的要求，可为蒸煮工艺的制定及生物质资源的利用提供参考。采用Design-Expert软件对慈竹DDS置换蒸煮进行了实验设计和结果评价、分析及优化。结果表明，热充段用碱量、硫化度、最高蒸煮温度和保温时间对卡伯值、细浆得率和白度影响明显；热充段用碱量对黏度的影响明显。在任一卡伯值下，纸浆的细浆得率、黏度和白度无法同时达到最优水平。基于Design-Expert的慈竹DDS置换蒸煮数学模型具有良好的预测和优化功能。在给定的工艺条件下，可以预测蒸煮的结果（卡伯值、细浆得率、黏度和白度）；在达到要求的蒸煮指标时，可通过实验优化制定出最佳的蒸煮工艺条件（预浸渍段用碱量、温充段用碱量、热充段用碱量、硫化度、最高蒸煮温度和保温时间）。对比DDS置换蒸煮与传统硫酸盐法蒸煮，慈竹DDS置换蒸煮成浆卡伯值低、得率高，且用碱量低。研究了慈竹无硫普通蒸煮工艺，讨论了添加助剂的慈竹无硫蒸煮与成浆性能的关系，并对比绿氧和自制蒸煮助剂对慈竹无硫蒸煮的影响。当绿氧用量为0.06%，用碱量为18%、最高蒸煮温度为160和用碱量为19%、最高蒸煮温度为155时所得纸浆性能相当，卡伯值为22左右，细浆得率49%左右，黏度1200mL/g，白度31%ISO左右。蒸煮时分别添加E、H、I三种自制助剂的用量为0.06%时，成浆卡伯值、细浆得率、黏度以及白度都和添加绿氧时相当。通过正交实验分析得出，采用DDS无硫置换蒸煮工艺，当助剂添加量分别为预浸渍段0.02%，温充段0.02%，热充段0.03%时，成浆卡伯值为23.6，细浆得率达到50.1%，黏度为1237mL/g，成浆性能几乎与慈竹DDS硫酸盐法蒸煮的纸浆性能相当。通过FT-IR分析可知，不同的蒸煮方式脱木素程度不同，纸浆中残余木素的结构有一定差异；自制助剂和绿氧结构不同，并且均有别于蒽醌，自制助剂在性能上和蒽醌有本质区别，提高了水溶性，并具有优良的蒸煮效果，但其具体结构还有待进一步分析。在慈竹硫酸盐法DDS置换蒸煮过程中，热充段用碱量、最高蒸煮温度对纸浆己烯糖醛酸的含量的影响显著；温充段用碱量、硫化度和保温时间的影响较小；预浸渍段用碱量影响最小。己烯糖醛酸含量的高低和纸浆卡伯值、细浆得率及纸浆黏度均没有明显对应关系。较少的有效碱用量、较低的蒸煮温度和较短的保温时间提高纸浆中己烯糖醛酸的含量，但纸浆的细浆得率也较高。研究了慈竹DDS置换蒸煮与纸浆ECF漂白和TCF漂白的相关性。结果显示，采用高温氧脱木素技术，当未漂浆卡伯值在18~20之间，氧脱木素后浆料性能较优。要达到85%ISO以上的目标白度，当未漂浆卡伯值小于10时，ECF（D0EopD1）漂白后纸浆黏度和得率均最低；当未漂浆卡伯值在12到20之间时，ECF漂白的有效氯用量和反应时间随卡伯值提高而增大，漂后浆黏度和得率均逐渐增加，当未漂浆卡伯值大于20时，漂后浆黏度略有下降、得率小幅度增加。卡伯值不同的未漂浆经TCF（QP1P2）漂白均不能达到85%ISO以上的白度。当未漂浆卡伯值小于10时，TCF漂白后纸浆黏度和得率均最低，分别为580mL/g和37.51%，总H2O2用量为3%，总漂白时间为270min，白度达到83.6%ISO；当未漂浆卡伯值在12到19之间时，TCF漂白的H2O2用量随卡伯值提高而增大，总H2O2用量在3.5%~4.0%，漂后浆白度在81.3~77.8%ISO，漂后浆黏度和得率均逐渐增加，黏度在634~650mL/g之间，得率在40.04%~40.98%之间；当未漂浆卡伯值大于19时，漂后浆黏度在634~588mL/g之间，得率在42.53%~43.48%之间，此时总H2O2用量在4.5%~5.0%，总漂白时间为270min，纸浆白度在76.1%~71%ISO之间。研究结果显示，ECF漂白在浆料白度、得率、黏度具有明显优势；而TCF漂白对浆料白度提高有限，只能在氧脱木素后卡伯值低于5时使用。采用FQA分析对比了慈竹DDS未漂浆、漂白浆和磨浆后的纤维形态、细小纤维含量等变化，纤维重均长度先略有增加后不断下降，纤维卷曲指数、纸浆中细小纤维含量逐渐下降，纤维扭结指数先下降后有所增加。磨浆后纤维重均长度由1.035mm降低到0.810mm，卷曲指数、扭结指数均下降，细小纤维含量增加幅度较大，升高为21.59%，这也是竹浆纤维与针叶木和阔叶木磨浆后浆料性能相差较大的原因之一。采用XRD、SEM和AFM对比研究了慈竹DDS置换蒸煮成浆ECF漂白和TCF漂白后纤维的特性，揭示了慈竹纸浆在制浆、磨浆不同阶段纤维表面形态的差别及表面特性的变化。慈竹DDS置换蒸煮成浆经漂白、磨浆后纸浆纤维素结晶度提高。慈竹DDS置换蒸煮后纤维表面有木素沉积，凹凸起伏较大；氧脱木素后去除了沉积在纤维表面的木素，纤维表面出现了长缝状的凹陷区域，起伏幅度减小；ECF漂白后纤维表面S1层微细纤维结构出现错位，分层现象，纤维表面粗糙度增加，说明对纤维影响程度较大；TCF漂白后纤维表面变化不明显，S1层微细纤维结构没有出现错位，分层现象，表明TCF漂白较ECF漂白温和，对纤维影响程度较小；磨浆后纤维表面局部的损伤程度显著增加，与前面SEM分析结果相同，进一步说明纤维素的部分无定形区受到破坏，纸浆结晶度提高显著。更多还原

【Abstract】 The shortage of wood fiber resources restricts the development of paperindustry in China for decades. Bamboo is widely distributed in China. The fibercharacteristics are similar to wood fibers, and the cost of bamboo pulp isrelatively lower than wood pulp, which can be potentially used as raw materialfor paper industry. Among the types of bamboo used as raw materials ofpapermaking, Neosinocalamus is one of the best candidates. The digesterdiagnosis system (DDS) is an energy-efficient and environmentally-friendlypulping method. Therefore, the development of DDS technology ofNeosinocalamus not only helps to alleviate the shortage of raw material in China,but also accords with the trend of green, environment-friendliness and lowcarbon in paper industry.In this work, the technologies of DDS replacement cooking and cleanbleaching were applied in Neosinocalamus pulping. The cooking parameters ofDDS replacement cooking and non-sulfur cooking with chemical aids wereinvestigated systematically, which indicated Neosinocalamus had the feature oflow-pollution. The correlation between DDS displacement cooking and cleanbleaching of Neosinocalamus was established combining the results from oxygendelignification, ECF and TCF bleaching, which helps to enrich the theoreticalsystem of clean pulping of Neosinocalamus.The effect of the parts and the storage period of Neosinocalamus on thechemical composition were studied. Neosinocalamus skin showed the highercontent in ash, alcohol-benzene extract than pole. Based on the results, one totwo months can be spent in the change in colour for Neosinocalamus beforepulping. The effect of pretreatment on the chemical composition of fiber and cooking properties of Neosinocalamus was also investigated. It is found thatsodium hydroxide and sodium sulphide can be used for pretreatment ofNeosinocalamus before cooking, which can reduce the content of lignin andprevent the excessive degradation of holocellulose. As compared to cookingconditions without pretreatment, the yield and the viscosity of bamboo pulp withpretreatment was lower but the Kappa number was decreased more significantly.These all satisfied the requirements of the use of commercial bleached pulp.Design-Expert software was employed to design and optimize theexperiment of DDS displacement cooking. It was found that alkali charge,sulfidity, max temperature and heat preservation time could affect the yield ofscreened pulp and brightness significantly in the stage of hot filling. Additionally,a remarkable impact of alkali charge on viscosity was also observed. For a givenKappa number, the optimal results of yield of screened pulp, viscosity andbrightness of pulp could not be obtained simultaneously. The mathematic modelof DDS displacement cooking built by Design-Expert software showed a goodresult in prediction and optimization.For a given parameters of cooking, the model can be used to predict theresults, including Kappa number, yield of screened pulp, viscosity and brightness.The cooking conditions, including the alkali charge in Initial Cooking（IC）,Initial Middle Cooking（IMC）and Final Middle Cooking（FMC）respectively,sulfidity, max temperature and heat preservation time can also be optimized.Compared to traditional kraft cooking, DDS displacement cooking ofNeosinocalamus had advantages of low Kappa number, high yield and low alkalicharge.The relationship between the conditions of non-sulfur cooking withchemical aids and pulp properties was analyzed and the comparison of greenoxygen and self-made cooking aids during non-sulfur cooking was alsodiscussed. When the usage of green oxygen was fixed at0.06%, the pulp properties from the cooking conditions of18%alkali and max temperature of160was similar to that of19%alkali and max temperature of155. Thecorresponding pulp properties were as follows: Kappa number of22, the yield ofscreened pulp of49%, the viscosity of1200mL/g and the brightness of30%ISO.The self-made cooking aids E, H, I can also achieved the pulp properties inKappa number, yield of screened pulp and brightness with the dosage of0.06%compared to green oxygen.The results of orthogonal experiment showed that when the usage ofcooking aids in IC, IMC and FMC was fixed at0.02%,0.02%,0.03%,respectively, the pulp properties was as follows: Kappa number of23.6, yield ofscreened pulp of50.1%, viscosity of1237mL/g. The pulp properties weresimilar to that of DDS kraft cooking. FT-IR results indicated the difference incooking method resulted in the variations in delignification and the structure ofresidual lignin. Unlike anthraquinone, the self-made cooking aids showed thegood solubility, which helps to improve the pulp properties. However, thechemical structure of self-made cooking aid needs to be analyzed further.During the DDS kraft cooking of Neosinocalamus, the akali charge and themax temperature of cooking had a significant effect on the content of HexA.There was no obvious correlation between the content of HexA and Kappanumber, yield of screened pulp and viscosity of pulp. It is found that low alkalicharge and cooking temperature, and short cooking time can improve the contentof HexA and the yield of screened pulp.The correlation between DDS displacement cooking of Neosinocalamusand ECF and TCF bleaching was investigated. It showed that the good pulpproperties can be obtained by oxygen delignification with high temperature whenthe Kappa number of unbleached pulp was18-20. The viscosity and yield of pulpwas lowest when adopting the bleaching sequence of D0EopD1with the Kappanumber below10. The chlorine demand, reaction time, viscosity and yield of bleached pulp with ECF sequence were increased as Kappa number increasedwhen the Kappa number of unbleached pulp was12-20. The viscosity ofbleached pulp decreased but a small increase of the corresponding pulp yield canbe observed when the Kappa number of unbleached pulp was more than20. Thebrightness of bleached pulp with TCF bleaching sequence (QP1P2) can notachieve85%. The viscosity and yield of bleached pulp with low Kappa number(less than10) of unbleached pulp were580mL/g and37.51%, respectively whenTCF bleaching sequence (QP1P2) was adopted. The bleaching conditions ofabove results were3%H2O2and reaction time of270min, the correspondingbrightness of pulp was83.6%ISO. The demand of H2O2with TCF bleachingincreased with increasing Kappa number from12to19. The brightness ofbleached pulp was in the range of81.3%~77.8%ISO with the dosage of H2O2were3.5%~4.0%, the corresponding viscosity and yield of bleached pulp werealso increased, which can be up to650mL/g and40.98, respectively. When theKappa number of unbleached pulp was more than19, the viscosity of bleachedpulp was in the range of634~588mL/g, and the yield was in the range of42.53%~43.48%. These results can be obtained when the usage of H2O2was4.5%~5.0%and the reaction time of270min, the corresponding brightness was76.1%~71%ISO. These results indicated ECF bleaching had advantages in pulpbrightness, yield and viscosity while the limited improvement in brightness canbe obtained by using TCF bleaching which can be adopted with Kappa numberof less5after oxygen delignification stage.The fiber morphology and fines content of unbleached pulp, bleached pulpand refined pulp of Neosinocalamus were compared by FQA analysis. Theresults showed that the weighted length, crimp index and fines content decreasedwith stages while the kink index of fiber was decreased firstly and then increasedafter bleaching. The weighted length of fiber decreased from1.035mm to0.810mm after refining. The crimp index and kink index decreased while fines content of fiber can be up to21.59%after refining, which is the major differencein bamboo fiber and wood fiber. XRD, SEM and AFM were used to investigatethe change in fiber properties of DDS pulp, ECF bleached pulp and TCFbleached pulp of Neosinocalamus. It is found that the crystallinity of fiber wasincreased with stages. The uneven lignin deposition can be observed on thesurface of fiber from DDS cooked pulp. Oxygen delignification removed thelignin deposited on the surface of fiber, resulting in the smoothed fiber surface.Dislocation and delamination can be observed in the structure of microfiber inS1layer after ECF bleaching. Meanwhile, the increase of the roughness of fibersurface verified fiber was damaged during bleaching. In contrast to EFCbleaching, the structure of microfiber in S1layer was not changed obviouslyafter TCF bleaching, indicating the bleaching condition of TCF bleaching ismilder. The increased degree of the damage of fiber further verified theamorphous region of fiber was damaged, resulting in the increase in crystallinityof pulp, which was accordance with SEM results.更多还原