【作者】 王旭青；

【导师】 周小凡；

【作者基本信息】 南京林业大学 ， 制浆造纸工程， 2011， 博士

【摘要】 本论文基于淀粉凝胶-溶胶机理和淀粉溶解机理,探索发明了不同的物理、化学方法改性淀粉,改善淀粉应用性能,并将这些改性方法和工艺实际应用于造纸工艺中的不同流程,得到了良好的应用效果。同时,利用红外光谱(IR)、光学显微镜和扫描电子显微镜(SEM)方法表征了凝胶淀粉和溶解淀粉的结构和功能。本研究主要创新点如下：(1)首次利用凝胶状的淀粉颗粒包覆填料粒子,是填料表面改性技术的又一创新；(2)在涂料配方中,将凝胶状的淀粉液代替部分胶乳,增大涂料中淀粉用量,降低胶乳用量；(3)首次探索了一种使淀粉在未充分蒸煮的情况下,形成凝胶状淀粉液的方法。将高固含量凝胶状淀粉液用于纸张表面施胶,提高纸张表面强度,降低干燥要求；(4)首次提出用NaOH/硫脲/尿素溶液直接对淀粉进行溶解达到糊化淀粉的目的。本学位论文研究内容和结果简述如下：(1)基于淀粉凝胶-溶胶机理,在造纸湿部应用中,采用新的改性工艺,成功制备出一种新型的表面包覆有阳离子凝胶状淀粉的填料粒子。此种填料粒子的颗粒大小可以调节控制,并分析了新型填料对湿部助留助滤性能、Zeta电位,以及用于手抄片后对纸张性能的影响。结果表明,改性过程中,淀粉糊化固含量对这种新型填料起着非常重要的作用,糊化浓度越高,填料颗粒平均直径越大；淀粉糊化固含量达到30%时,新型填料达到最优的使用效果,即填料具有最好的助留助滤效果,用于手抄片后,和只加填PCC手抄片相比,纸张的灰分提高37.5%,抗张指数提高41.1%,耐破指数提高50%,表面强度提高45.3%；(2)基于淀粉凝胶-溶胶机理,在造纸涂料应用中,采用新的改性工艺,成功制备出凝胶状淀粉液,用于代替涂料中的部分胶乳。结果表明,在相同涂料配方情况下,凝胶状淀粉涂料无论低剪切黏度还是高剪切黏度均低于糊化淀粉涂料,凝胶状淀粉涂料保水值低于糊化淀粉涂料；用于纸张涂布后,凝胶淀粉涂布纸在CIE白度、平滑度、K&N值、表面强度方面等性能优于糊化淀粉涂布纸,优化的涂料配方6#(碳酸钙：瓷土：淀粉：胶乳的绝干量的比为60：40：12：5)具有最优的性能,充分表明用凝胶淀粉液代替涂料中部分胶乳可以实现；(3)基于淀粉凝胶-溶胶机理,在造纸表面施胶应用中,用凝胶状淀粉液代替传统糊化淀粉液,制备出高固含量凝胶状淀粉表面施胶液。结果表明,相比传统8%固含量糊化淀粉液,高固含量凝胶状淀粉液能大大提高纸张的表面强度,纸张物理强度和光学性能略有改善,但抗水性能差；(4)为了进一步降低淀粉黏度,研究发现一种新型的用NaOH/硫脲/尿素溶液直接溶解淀粉的方法。结果表明,溶解温度在-10℃时,当NaOH用量为4%,硫脲用量为3%,尿素用量为3%时,该溶解体系的溶解淀粉液黏度最低；溶解淀粉液用于纸张表面施胶后,纸张物理强度、不透明度、平滑度和表面强度得到提高；溶解淀粉液的固含量越高,纸张的平滑度和表面强度越高。更多还原

【Abstract】 Based on sol-gel and starch dissolution mechanism, different physical or chemical methods were used to modify starch in this work. At the same time, the use of modified starch in the different processes of papermaking industry obtained excellent practical effect. IR analysis, optical microscope, and Scanning Electron Microscope(SEM) were applied to characterize the structure and function of gel starch and dissolved starch.The novel development of this work is as follow:(1) Filler was wrapped with gel starch for the first time. It is another innovation among the surface modified technologies of filler;(2)In the recipe of coating color, latex is replaced with gel starch to increase the dosage of starch while decrease the dosage of latex;(3) It is the first time to explore a method which make the gel starch from not sufficiently cooking starch. In order to improve surface strength of paper and decrease dry capacity, high solid content of gel starch was used as sizing agent. (4) The dissolved starch solution can be used as sizing agent directly after its dissolution by NaOH/thiourea/urea, no need of cooking.The content and results of this work are as follow:(1) Based on the sol-gel mechanism, a novel filler wrapped with cationic gel starch was prepared successfully in wet end application through adopting new modified technology. The particle of this novel filler can be controlled. We also analysised the retention and drainage property, Zeta potential, and the properties of papers. The results revealed that, the cooking solid played an important role in the modification process, the mean diameter of filler was bigger as the cooking solid was higher. When the solid of starch was up to 30%, the novel filler had the optimal application effect, which had the highest filler retention compared with the raw paper, improved 37.5% of the ash content,41.1% of the tensile index,45.3% of the surface strength. (2) Based on the sol-gel mechanism, the gel starch was prepared in the coating system application through adopting new modified technology. This kind of gel starch was used to replace latex in coating color. The results revealed that, the low and the high shear viscosity, the water retention property of gel starch coating color were lower than cooking starch coating color. The papers surface sized with gel starch coating color had better properties than that sized with cooking starch coating color, such as CIE whiteness, smoothness, K&N value, surface strength. The optimal 6#(the dry dosage of GCC:Clay:Starch:Latex is 60:40:12:5) coating recipe had greatest property, it also indicated that it is feasible to replace latex with gel starch in coating color. (3) Based on the sol-gel mechanism, the gel starch was prepared in the surface sizing system application through adopting new modified technology. This kind of gel starch was used to prepare the high solid content of surface sizing agent. The results revealed that, the high solid content of gel starch solution improved the surface strength, physical strength and optical property of paper compared with 8% solid content cooking starch, but the papers surface sized with gel starch had worse water resistant property. (4) In order to decrease the viscosity of starch solution, a novel method of dissolving starch in NaOH/thiourea/urea solution was found. The results showed that, the dissolved starch solution had the lowest viscosity as the temperature of dissolution system was -10℃, and the dosage proportion of NaOH,thiourea,urea was 4:3:3.The papers surface sized with dissolved starch had better physical strength, opacity, smoothness, surface strength. When the solid content of dissolved starch was higher, the papers got better smoothness and surface strength.更多还原