PURPOSE: To obtain the title polymer emulsion of good mechanical and standing stability, by polymerizing vinyl chloride or its mixture with another monomer in the presence of a polyvinyl alcohol having sulfonic group, a water-soluble catalyst, and a specific inorganic salt to prevent flocculate formation.

CONSTITUTION: The objective polymer emulsion can be prepared by polymerizing A) vinyl chloride or its mixture with copolymerizable another ethylenic unsaturated monomer, in the presence of B) a polyvinyl alcohol having sulfonic or sulfuric group, C) a water-soluble catalyst, and D) an alkali metal or ammonium sulfate, its chloride, etc. The amount of the component D) is preferably 0.05W1wt% based on the component A). The component A) is desired to be a mixture consisting of 30W 70wt% of vinyl chloride and 70W30wt% of an unsaturated carboxylic ester.

EFFECT: Capable of effectively preventing flocculate formation in the presence of the inorganic salt.