Polyester-modified vinyl resin

A silyl group-containing, polyester-modified vinyl polymer comprising

• (A) 3 to 45% by weight of units of a polyester resin including a polymerizable unsaturated group,
• (B) 5 to 30% by weight of units of a silane compound of the formula (I):
• ##STR6## wherein R.sup.1 is hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms selected from the group consisting of an alkyl group, an aryl group and an aralkyl group, R.sup.2 is an organic residue having a polymerizable double bond, X is a hydrolyzable group and n is an integer of 1 to 3, and
• (C) 25 to 92% by weight of units of a copolymerizable vinyl monomer mixture of a vinyl monomer having no polar group and a vinyl monomer having a polar group selected from the group consisting of a carboxylic acid group, an acid anhydride group, an epoxy group, an amino group, an amido group and a hydroxyl group, which is prepared by polymerization of said polyester resin, said silane compound, and said vinyl monomer mixture in the presence of a solvent, or which is prepared by first polymerizing said polyester resin and said vinyl monomer mixture, and then reacting said silane compound with the resulting product.