使用特殊聚乙烯醇作为保护胶体和喷雾助剂的高性能可再分散乳胶粉

High-performance re-dispersible powders using special polyvinyl alcohol as a protective colloid and a spray aid

以特殊聚乙烯醇(PVA)作为保护胶体和喷雾助剂喷雾干燥醋酸乙烯酯-乙烯共聚物乳液(VAE-EM)制备了高性能可再分散乳胶粉。作为保护胶的特殊聚乙烯醇使醋酸乙烯酯-乙烯共聚物乳液(VAE-EM)含有大量的接枝聚乙烯醇,这有利于在水中获得良好的再分散性。含有疏水基的特殊聚乙烯醇作为喷雾助剂使再分散薄膜具有很好的耐水性。对用多种特殊聚乙烯醇制成的胶粉作为砂浆添加剂进行评价,结果表明,掺高性能再分散胶粉的砂浆抗弯强度和粘结强度明显优于掺普通再分散胶粉的砂浆。该砂浆添加剂中作为保护胶体和喷雾助剂的聚乙烯醇对胶粉的再分散性影响很大。

High-performance re-dispersible powders were prepared by spray drying of vinyl acetate-ethylene co-polymer emulsion（VAE-EM） having special polyvinyl alcohol（PYA）as a protective colloid and a spray aid.The special PVA as a protective colloid made VAE-EM having higher amount of grafted PVA, and which was useful in getting excellent re-dispersibility in water. The other special PVA having hydvophobic group as a spray aid gave high water resistance to a film of re-dispersion.The powders prepared by using special PVAs in this study were evaluated as an additive for mortar.As a result,the mortars had much better bending strength and adhesive strength comparing with mortars containing commercial re-dispersible powder.It should be considered that the re-dispersibility of powder was very important for the performance of re-dispersible powder as an additive for mortar and was strongly influenced by PVAs used as a protective colloid and a spray aid.