PURPOSE: To impart excellent mechanical stability to a polymer obtd. by forming the reactive emulsifier expressed by specific general formula and various properties, such as emulsification stability, water resistance, adhesiveness, and gloss, to the resulted emulsion and to form a stable coated film.
CONSTITUTION: The reactive emulsifier expressed by the general formula 1 is formed. In the formula, R1 denotes a hydrogen atom or methyl group. R2 denotes a residual group occurring in 3 to 9C acid anhydride compd. A denotes a residual group occurring in stabilized rosin. M denotes an alkalimetal ion, ammonium group or tertiary amine. The rosin skeleton is introduced into the resulted polymer and the emulsion having the excellent emulsification stability is obtd. if such reactive emulsifier is used as an emulsifier for emulsion polymn. The film which is excellent in the various properties, such as water resistance, adhesiveness and gloss, is obtd. if such emulsion is used for applications of adhesives, coating materials, ink, etc.