Abstract
The effect of polyvinyl alcohol (PVA) added after polymerization on polyvinyl acetate (PVAc) emulsion obtained in the system having no protective colloids were studied in regard to coagulation by sodium sulfate. Both PVA emulsion and PVAc emulsion, in which perfectly saponified PVAc and partially acetylated PVA were added were easily coagulated by sodium sulfate. But emulsion in which partially saponified PVAc was added had the excellent stability against sodium sulfate. With partially saponified PVAc obtained by ordinary alkali saponification of PVAc in methanol, the effect of the stability against sodium sulfate became higher as the residual acetyl content were increased and the residual acetyl groups were maldistributed in a polymer chain. It was concluded that partially saponified PVAc having the residual acetyl groups maldistributed in a polymer chain absorbed on the surface of the particles of PVAc and the hydrophilic phase were formed on the surface of the particles of PVAc by the hydroxyl groups maldistributed in a polymer chain of partially saponified PVAc absorbed.
