【作者】 张国平；

【导师】 包永忠； 张成德；

【作者基本信息】 浙江大学 ， 化学工程， 2002， 硕士

【摘要】 本文以大口径管材专用聚氯乙烯（PVC）树脂的工业开发为背景，结合氯乙烯悬浮聚合成粒机理，建立了合成大口径管材专用PVC树脂的成粒路线，在5升聚合釜进行合成规律基础研究，采用优化的配方和工艺在100升釜进行工程放大，得到颗粒形态规整、表观密度较高、干流性和凝胶化性能良好的专用树脂。 高表观密度PVC树脂是目前研制大口径管材专用树脂的主流方向，球形PVC树脂并未大规模生产；收集、剖析了国内外部分厂家的高表观密度、球形PVC树脂样品和标准，发现质量优良的大口径管材专用树脂颗粒一般呈规整的棉桃形，颗粒分布集中，细粒很少，颗粒内部闭孔少。根据专用树脂的颗粒特性，在已有氯乙烯悬浮聚合成粒机理基础上，设计了大口径管材专用树脂成粒路线：采用特定的分散体系并结合连续添加分散剂工艺和搅拌模式。 对5升聚合釜的搅拌桨型进行改进，开发了效果较好的复合桨桨型；对多种分散体系及加料方式进行了试验，结果证明采用充N₂气聚合可抑制单体回流，大幅度降低分散剂用量至大釜相当水平；采用部分分散剂在聚合开始后连续加入可明显改善树脂颗粒形态，提高表观密度，改善干流性，并对其改善颗粒形态的机理作了理论分析，指出聚合过程中改善颗粒形态的推动力是界面张力产生的附加压强，大小不同的颗粒在聚合过程中受到的附加压强不同，造成颗粒的疏松程度不同；由表观密度和吸油率可近似计算出粒间孔隙率和粒内孔隙率，用以树脂总体积为基准的粒间孔隙率和粒内孔隙率可直观地反映树脂颗粒堆积密度，准确评判树脂质量的优劣。对连续添加分散剂工艺进行了详细研究，优化了分散剂前加比例、添加速度等对聚合稳定性和树脂颗粒特性有明显影响的操作参数，获得了稳定的工艺，制得表观密度≥0.55g／ml，吸油率≥20％的树脂。 对优化的小试专用PVC树脂样品的颗粒内部形态、比表面积和加工性能的研究表明：小试样品的颗粒内部初级粒子聚集程度较小，比表面积较大，采用比表面积可以更好反映树脂的凝胶化特性；颗粒分布集中的树脂能获得高表观密度、干流性好的混合料；分析了凝胶化性能测试过程的实质并结合试验结果，提出颗粒外形是影响树脂凝胶化性能的一个重要因数的观点，颗粒外表过于圆滑的树脂凝胶化性能不好；指出加工混合料的质量才是最终决定挤出速度的因素，树脂的质量最后应由加工混合料的质量评定。 浙江大学硕士论文 分析了100升聚合釜的搅拌特性，并对搅拌桨型进行了优化，通过100升釜聚合进一步优化了分散剂用量和连续添加分散剂工艺，制备得到颗粒形态规整、干流性和加工凝胶化性能良好的中试产品，经工业挤出管材实验表明，采用中试专用 PVC树脂，挤出速度有一定的提高。更多还原

【Abstract】 Aiming at industrial development of poly(vinyl chloride) resin for rigid pipe with great diameter, a particle formation approach of this special-use PVC resin was proposed based on the well-known particle formation mechanism of vinyl chloride suspension polymerization. The basic research on systhesis laws was carried out in a 5 liter autoclave and pilot research was carried in a 100 liter autoclave using the optimized recipe and technology. PVC resin with regular particle shape, high bulk density, good powder flowability and gelation property was prepared.PVC resin with high bulk density is the main direction for producing the special PVC for pipe with great diameter, spherical PVC hasn’t ever been produced wholesale. Some PVC samples and standards of domestic and international companies have been collected and analyzed, it was found that pipe grade PVC with excellent quality often show plump-like particle shape, narrow particle-size distribution, few fine particles and few closed sell inside particles. A particle formation course of pipe grade PVC resin was designed as: using specific dispersant system, specific dispersant injection mode and specific agitation mode.Agitation for the 5L autoclave has been improved and an agitator with good agitation effect has been developed. Many dispersant system and dispersant injection modes were applied in the polymerization. It was observed that injection of Na gas to the polymerization system could decrease the amount of dispersant agent to level comparable to that of industrial production by restraining the monomer flow back. Injection of part of dispersant agent continuously during the polymerization could perfect particle shape effectively, increase bulk density, improve power flowability. The principle of perfecting particle shape was analyzed theoretically and it is proposed that the draw-force of perfecting particle shape is the additional pressure produced by interfacial tension, the additional pressure on particles with different diameter are different, which would lead to different in porosity. The porosity inside and outside particles was calculated from bulk density and cold plasticizer absorption and could be used to characterize the accumulative density and to reflect the quality of PVC. The continuous injection mode was studied indetail, and factors affecting the stability of polymerization and particle features of resin,such as the ratio of initial added dispersant agent(s) to the total amount dispersant agentsand the addition rate of dispersant agents, were optimized. PVC resin with bulk density ≥0.55g/ml, cold plasticizer absorption ≥20% were prepared, using the optimized recipeand technology.The internal particle morphology, special area and the processability of PVC wereinvestigated in detail, it was found that the aggregation degree of parimary particles in theoptimized PVC resins was lower and special area was relatively greater. A combinationof high bulk density and good flowability was obtained by using PVC with a narrowparticle-size distribution. The gelation course of PVC compound was analyzed and it wasproposed that particle’s shape was an important factor influencing the gelation of PVC.The gelation property of PVC resin with excessively round and slick particle shape whouldbe bad. It was also proposed that properties of PVC compound were the final determinantsof the extrusion speed.The agitation features of the 100L autoclave were analyzed and the agitator wasoptimized. The usage of dispersant agents and the technology of continuous injection ofdispersant agents were optimized through polymerizations carried on the 100L autoclave.PVC resin with regular particle shape, higher bulk density and excellent powderflowability and gelation properties were obtained and used in the industrial production ofpipe. The extrusion speed increased as special-use PVC resin prepared by this work wasused.Key words: Polyvinyl chloride, suspension polymerization, rigid pipe with great di更多还原