a water - soluble coating composition adapted for imparting appropriate printing , especially off - set printing , and processing characteristics to a thermoplastic resin film to be used as a synthetic paper and a coated film prepared with the composition are provided . the coating composition comprises 100 parts by weight of a water - soluble polymer containing tertiary or quaternary nitrogen , 5 to 75 parts by weight of a water - soluble polyaminepolyamideepichlorohydrin adduct , and 5 to 100 parts by weight of a water - soluble polyimine compound .