干燥预处理对EVA可再分散乳胶粉性能的影响

Effect of predisposal for drying on performance of EVA redispersible emulsion powder

通过试验用NaOH稀溶液、硅溶胶和聚乙烯醇(PVA)对乙烯-醋酸乙烯酯(EVA)乳液进行干燥预处理,采用喷雾干燥法制备EVA可再分散乳胶粉,并讨论pH值、硅溶胶、PVA对EVA可再分散乳胶粉含水率、残渣率、再分散性及再分散液胶膜等性能的影响.试验结果表明,将EVA乳液pH值调节至9,用乳液质量25%的硅溶胶和5%的PVA对乳液进行干燥预处理,在雾化机旋转盘转速为21000r/min,进出口温度分别为170℃和90℃,进料速度为80g/min条件下进行喷雾干燥,制得的EVA可再分散乳胶粉含水率(ω=2.35%)和残渣率(ω=3.70%)低、再分散性及再分散液成膜良好.

Ethene-vinyl acetate（EVA）redispersible emulsion powder was prepared via spray drying after the emulsion was predisposed with dilute sodium hydroxide solution, silica sol and polyvinyl alcohol （PVA） through experiment. The effects of pH value, silica sol and PVA on the powder＇s water and filter residue content, redispersibility and film properties of reconstituted emulsion were discussed. The experimental results show that pH value of EVA emulsion is adjusted to 9 and silica so1（25% of EVA emulsion） and PVA（5% of EVA emulsion） are added to the emulsion, under the conditions of rotating speed of atomizer of 21 000 r/min, inlet and outlet temperatures of 170 ℃ and 90 ℃ , and charging rate of 80 g/min. EVA redispersible emulsion powder can be obtained with low water content（to = 2.35% ） and filter residue content（to = 3.70% ） , which has good redispersibility, and the reconstituted emulsion shows good film forming property.