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 ℃.