PURPOSE: To provided a primer compsn. which is applied to the surface of a molded article to improve the adhesion between the article and a coating film formed thereon without requiring the vapor cleaning of the surface with an org. chlorinated solvent such as trichloroethylene or 1,1,1-trichloroethane.

CONSTITUTION: A primer compsn. is prepd. by compounding 5-50 pts.wt. chlorinated graft copolymer with 95-50 pts.wt. org. solvent. The copolymer is prepd. by chlorinating a graft copolymer obtd. by grafting at least one monomer selected from the group consisting of an unsatd. carboxylic acid and its anhydride onto a random copolymer obtd. from propylene and at least one monomer selected from the group consisting of ethylene and a 4C or higher α-olefin.