无皂沉淀法制备聚乙烯醇缩丁醛

Synthesis of Polyvinyl Butyral via Soap-free Precipitation Method

通过无皂沉淀法，以纳米二氧化硅替代表面活性剂，将丁醛通过高压均质机分散到聚乙烯醇水溶液中，制备了缩醛基含量75％以上，溶液黏度与市售树脂相当的聚乙烯醇缩丁醛（PVB）树脂（平均聚合度1700）。所得的PvB树脂粉末由粒径小于10μm的原始颗粒团聚而成，证明反应是在微小体积内进行；纳米二氧化硅黏附在颗粒的表面，起到了很好的物理隔离的作用，有效的抑制了PVB的团聚。无皂沉淀法减少了树脂洗涤用水的消耗，并且有利于树脂品质的提高。优化的反应条件为：聚乙烯醇和丁醛质量比为1；（0．60-0．65），反应起始温度20℃，梯度升温速度为5℃／30min，pH=1．3，分散剂纳米二氧化硅用量为体系的0．07％。

A novel soap-free precipitation method was adopted to prepare polyvinyl butyral （PVB）. Nano-silica was selected as a dispersant in place of the surfactant. Butyraldehyde was dispersed into the aqueous solution of polyvinyl alcohol （PVA） by high pressure homogenization. The resulted PVB powder was aggregates of primary particle which was less than 10 microns, indicating that the reaction was carried out within a small volume. Nano-silica adhered to the surface of the particle, and effectively inhibited the agglomeration of PVB via the physical isolation. The acetal group content of the PVB was above 75% and the viscosity of its ethanol solution was similar to that of the commercial resins. The soap-free precipitation method evidently reduced the consumption of washing water and improved the quality ofthe resin. The optimized reaction conditions were. mass ratio of PVA to butyraldehyde 1 ： （0. 640. 65）, starting temperature 20 ℃, gradient heating rate 5 ℃/30 rain, pH value 1.3, dosage of nano-silica 0. 07 % of the total system.