【作者】 秦少雄；

【导师】 陈焕钦；

【作者基本信息】 华南理工大学 ， 化学工程， 2006， 博士

【摘要】 水性建筑乳液涂料具有环保、性能优良的特点，但配方中近一半是水，同时为保证涂料的存储和使用性能必须加入大量的其他助剂(如：增稠剂、消泡剂、成膜助剂、分散剂、防霉剂等)，不仅增加了成本，也造成了资源的浪费。如果能将建筑涂料制成干粉形式，采用纸袋包装，制成所谓“干粉涂料”，这种涂料是由可再分散乳胶粉与必要的其他组份如填料、颜料、成膜助剂等组成。在使用时加水调和“干粉涂料”又变成通用的乳液建筑涂料。这样，不仅可以降低包装运输费用、减少助剂使用量，而且延长存储周期、给施工带来方便。制造干粉涂料的关键技术是将水性涂料中的成膜物质乳液干燥成粉末状成膜物质可再分散乳胶粉。 为了制造干粉建筑涂料，必须加强可再分散乳胶粉专用乳液的合成方法和干燥这种乳液为粉末的工艺研究。本论文通过可再分散乳胶粉分散原理再分析，探究了其专用乳液的结构特点，围绕聚丙烯酸酯类乳液聚合及其乳液喷雾干燥，进行了下面几方面的研究： 一、种子乳液聚合过程中，在引发剂作用下单体接枝到水溶性纤维素醚—羟乙基纤维素(HEC)上形成的接枝共聚物聚集形成初始乳胶粒，然后直接滴加单体，通过半连续种子乳液聚合方法制备了HEC稳定的聚丙烯酸酯类乳液，乳液分离后不溶物的红外光谱和乳液乳胶粒透射电镜(TEM)证实了接枝共聚物的这种结构。这种工艺具有高分子乳化剂合成和乳液聚合一步连续完成，工艺简单、操作容易控制的特点，为水溶性高分子用于乳液聚合开拓了一条新思路。 二、系统研究了温度、种子聚合时间、HEC用量、引发剂用量和混合单体比例对乳液聚合和接枝反应的影响，并采用粒度分析仪和重量法对乳液聚合过程中乳胶粒子的成长过程和乳液聚合的动力学特征进行考察。结果表明：种子乳液聚合阶段，HEC的降解与接枝使乳胶粒粒径随种子聚合时间延长而减小，种子聚合时间90min为宜(单体转化率80.4％，90min粒径稳定为119.6nm)；乳胶粒长大阶段，由于空间位阻效应，单体的聚合速率随乳胶粒粒径增大而减小，体系中存在二次成核现象，二次成核几率随HEC用量增加而增大；整个长大过程乳胶粒瞬时转化率不高；聚合结束后，适当延长保温时间单体转化率可达到95.88％。这些研究优化了乳液聚合工艺。 三、HEC稳定的聚丙烯酸酯类乳液乳胶粒表面有一层牢固锚定、较厚的保护层，其非离子性使乳液具有优良的电解质稳定性、冻融稳定性和稀释稳定性；乳胶膜力学性能比常规乳液胶膜力学性能有很大提高；流变性研究表明：这类乳更多还原

【Abstract】 Waterborne architectural coatings possess a lot of advantages, such as environmental protection and excellent performance, but there is nearly half of water in the waterborne coatings. At the same time, in order to ensure storage and service performance of the coatings, a lot of assistants, such as thickener, antifoam agent, coalescing agent, dispersant and mildew preventive, have to be added, so that not only raised the costs of coatings but also wasted resource. These disadvantages can be overcome if the shape of the coatings could be changed from liquid to solid powder called "dry coatings" which are consist of redispersible powders and necessary components such as extender, pigment and coalescing agent, and it can be packaged by a paper bag. When a duilding site needs to spray or brush a coating, the dry coating and some water were put into a container and stired them for a while to become usual latex coatings. Making dry coatings in this way not only decrease the costs of package, transport, and dosage of assistants, but also prolong storage period, and bring convenient application. The key technology for making dry coating is that the shape of film forming polymer should be changed from liquid emulsion to solid powder which must be redispersible in water.In order to make dry architectural coating, it must be strengthened to research the methods of synthesizing various redispersible polymer emulsions and drying the emulsion to powder. In this dissertation, the structural characteristic of special emulsion was explored by re-analyzing dispersible principle of redispersible powder. Surrounding the emulsion polymerization of polyacrylate and its drying process, the following studies were carried out:1) Monomers were grafted onto water-soluble cellulose ether, i.e. HEC under the action of initiator to form prime particles during the course of seeded emulsion polymerization, then monomers were added directly, and the polyacrylate emulsions stabilized by HEC were prepared via semi-continuous seeded emulsion polymerization. The structure of the grafted copolymer was confirmed via characterizing the insoluble substance which was separated from emulsion by FTIR and developing the figure of the emulsion particles by TEM. This technology of polymerization possesses a lot of merits, such as the synthesis of polymeric emulsifier and emulsion polymerization were completed continually in one step,更多还原