喷雾干燥法制备可再分散苯丙乳胶粉的研究

发布时间：2018-03-16 10:48

  本文选题：可再分散乳胶粉　切入点：核壳结构　出处：《华南理工大学》2010年硕士论文　论文类型：学位论文

【摘要】： 可再分散聚合物乳胶粉是一种加水能重新分散在水中形成分散液,并具有与原乳液相似性能的聚合物粉末。一般是由聚合物乳液经保护胶体等改性后,通过喷雾干燥而制得。少量可再分散乳胶粉添加于水泥基干粉建材中可改善其多种性能,因而广泛应用于多个领域。随着干粉建材的日益发展以及人们对建材性能的要求的提高,高性能的可再分散乳胶粉的需求越来越大。 本文通过粒子设计理论制备出具有“软核硬壳”结构的苯丙乳液,并通过喷雾干燥制备出性能优异的可再分散乳胶粉。重点探讨了喷雾干燥过程对乳胶粉性能的影响。 (1)采用半连续种子乳液聚合工艺,以甲基丙烯酸甲酯(MMA)和苯乙烯(St)为硬单体、以丙烯酸丁酯(BA)和丙烯酸异辛酯(2-EHA)为软单体、以甲基丙烯酸(MAA)和甲基丙烯酸羟丙酯(HPMA)为功能单体,制备了具有核壳结构的苯丙乳液。实验结果表明,当壳层Tg达到65℃～75℃,总Tg为0℃～5℃、乳液粘度为91.5 mPa·s、粒径为114nm、固含量为45%时,乳液较适合于喷雾干燥。 (2)采用保护胶体和强碱对苯丙乳液进行改性。研究结果表明,当选用聚合度为500、水解度为88%的聚乙烯醇(PVA-205)作为保护胶体、PVA用量为4%～6%(占乳胶粉质量百分比,下同)、采用5%的氢氧化钠溶液(质量浓度)、其用量为将喷雾液pH值调节至9、将调碱后的喷雾液放置5小时、再将喷雾液的粘度控制在15～20s时,配制的喷雾液较适合喷雾干燥。 (3)无机抗结块剂在可再分散乳胶粉中能够阻止乳胶粉粒子相互接触而发生结块,提高储存稳定性并且可以降低乳胶粉的成本。经试验表明,采用超细硅酸铝作为无机抗结块剂,并在喷雾干燥后加入,加入量为10%～12%,可显著提高乳胶粉的储存稳定性。 (4)通过调节喷雾干燥过程的各种参数,实验结果表明,当喷雾干燥的进口温度为120～140℃、出口温度为70～80℃、、雾化盘为满负荷运转且转速为24000 r·min-1、进料泵转速为30～35 rpm时,可得到性能较好的可再分散乳胶粉。 通过喷雾干燥法制备的可再分散苯丙乳胶粉,其再分散性能优异、流动性好、储存稳定优良的耐碱性和性价比较高。
[Abstract]:Redispersible polymer latex powder is a kind of polymer powder which can be dispersed in water by adding water and has similar properties to the original emulsion. A small amount of redispersible latex powder can be added to cement based dry powder building materials to improve its performance. With the development of dry powder building materials and the improvement of the performance of building materials, the demand of high performance redispersible latex powder is increasing. In this paper, styrene-acrylic emulsion with "soft core-hard shell" structure was prepared by particle design theory, and redispersible latex powder with excellent properties was prepared by spray drying. The effect of spray drying process on the properties of emulsion powder was discussed. 1) the semicontinuous seed emulsion polymerization process was carried out, using methyl methacrylate (MMA) and styreneol (St) as hard monomers, butyl acrylate (BA) and isooctyl acrylate (2-EHA) as soft monomers, and methacrylate (MAA) and hydroxypropyl methacrylate (HPMA) as functional monomers. A styrene-acrylic emulsion with core-shell structure was prepared. The experimental results show that the emulsion is suitable for spray drying when the shell layer TG reaches 65 鈩，

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