丙烯酸(酯)改性聚醋酸乙烯酯乳液的研制

采用半连续种子乳液聚合法,使用丙烯酸(AA)功能性单体和丙烯酸丁酯(BA)软单体对醋酸乙烯酯(VAc)进行了共聚改性,制备出高固含量(50.2%)的聚醋酸乙烯酯(PVAc)改性乳液。该乳液适合用于喷雾干燥法制备可再分散聚合物粉末,并且其耐水性和耐碱性等都得到了明显地改善。对影响共聚物的诸多因素进行了较为全面地考察,得出最佳的工艺条件为:AA用量为主单体质量的3%～4%,BA用量为主单体质量的5%～10%,保护胶体用量为混合单体质量的7.5%～15%,引发剂用量为混合单体质量的0.4%～0.5%,阴/非离子型复合乳化剂的质量比为1∶2～1∶3、用量为混合单体质量的2%～3%,分散剂、消泡剂和酸碱缓冲剂等助剂均为适量,加料时间为3～4h,反应温度为70～75℃。

Study on preparation of modified poly(vinyl acetate)emulsion with acrylic acid and butyl acrylate

Poly (vinyl acetate)(PVAc) modified emulsion of high solid content (50.2%) was prepared by semi-continuous seeded emulsion polymerization. The redispersible polymer powder was produced properly by spray drying with it. In the copolymerization system,PVAc emulsion was modified via vinyl acetate(VAc) as main monomer,acrylic acid(AA) as functional monomer and butyl acrylate(BA) as soft monomer. The water resistance,alkali resistance and other performances were improved obviously. Many effect factors of copolymerization were discussed particularly,and the optimal craft condition were decided:mass fraction of AA was between 3% and 4% in main monomer dosage,mass fraction of BA was between 5% and 10% in main monomer dosage,mass fraction of protective colloid was between 7.5% and 15% by weight of mixed monomer,mass fraction of initiator was between 0.4% and 0.5% by weight of mixed monomer,mass ratio of anion and non-ion in complex emulsifier were between 1∶2 and 1∶3,mass fraction of complex emulsifier was between 2% and 3% by weight of mixed monomer,the dosage of dispersant,defoaming agent,acid and alkali buffering agent,and other addition agent were right amount,time of adding materials was between 3 h and 4 h,and polymerization temperature was between 70 ℃ and 75 ℃.