本文選題：可再分散乳膠粉　切入點：核殼結(jié)構(gòu)　出處：《華南理工大學》2010年碩士論文　論文類型：學位論文

【摘要】： 可再分散聚合物乳膠粉是一種加水能重新分散在水中形成分散液,并具有與原乳液相似性能的聚合物粉末。一般是由聚合物乳液經(jīng)保護膠體等改性后,通過噴霧干燥而制得。少量可再分散乳膠粉添加于水泥基干粉建材中可改善其多種性能,因而廣泛應用于多個領域。隨著干粉建材的日益發(fā)展以及人們對建材性能的要求的提高,高性能的可再分散乳膠粉的需求越來越大。 本文通過粒子設計理論制備出具有“軟核硬殼”結(jié)構(gòu)的苯丙乳液,并通過噴霧干燥制備出性能優(yōu)異的可再分散乳膠粉。重點探討了噴霧干燥過程對乳膠粉性能的影響。 (1)采用半連續(xù)種子乳液聚合工藝,以甲基丙烯酸甲酯(MMA)和苯乙烯(St)為硬單體、以丙烯酸丁酯(BA)和丙烯酸異辛酯(2-EHA)為軟單體、以甲基丙烯酸(MAA)和甲基丙烯酸羥丙酯(HPMA)為功能單體,制備了具有核殼結(jié)構(gòu)的苯丙乳液。實驗結(jié)果表明,當殼層Tg達到65℃～75℃,總Tg為0℃～5℃、乳液粘度為91.5 mPa·s、粒徑為114nm、固含量為45%時,乳液較適合于噴霧干燥。 (2)采用保護膠體和強堿對苯丙乳液進行改性。研究結(jié)果表明,當選用聚合度為500、水解度為88%的聚乙烯醇(PVA-205)作為保護膠體、PVA用量為4%～6%(占乳膠粉質(zhì)量百分比,下同)、采用5%的氫氧化鈉溶液(質(zhì)量濃度)、其用量為將噴霧液pH值調(diào)節(jié)至9、將調(diào)堿后的噴霧液放置5小時、再將噴霧液的粘度控制在15～20s時,配制的噴霧液較適合噴霧干燥。 (3)無機抗結(jié)塊劑在可再分散乳膠粉中能夠阻止乳膠粉粒子相互接觸而發(fā)生結(jié)塊,提高儲存穩(wěn)定性并且可以降低乳膠粉的成本。經(jīng)試驗表明,采用超細硅酸鋁作為無機抗結(jié)塊劑,并在噴霧干燥后加入,加入量為10%～12%,可顯著提高乳膠粉的儲存穩(wěn)定性。 (4)通過調(diào)節(jié)噴霧干燥過程的各種參數(shù),實驗結(jié)果表明,當噴霧干燥的進口溫度為120～140℃、出口溫度為70～80℃、、霧化盤為滿負荷運轉(zhuǎn)且轉(zhuǎn)速為24000 r·min-1、進料泵轉(zhuǎn)速為30～35 rpm時,可得到性能較好的可再分散乳膠粉。 通過噴霧干燥法制備的可再分散苯丙乳膠粉,其再分散性能優(yōu)異、流動性好、儲存穩(wěn)定優(yōu)良的耐堿性和性價比較高。
[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，

本文編號：1619595