Abstract: A method for the manufacture of a polybutadiene-modified unsaturated polyester, comprising the steps of: (I) reacting (A) an .alpha.,.beta.-unsaturated dicarboxylic acid or anhydride with (B) at least one compound selected from the group consisting of (i) air-drying allyl compounds, (ii) animal and vegetable oils or derivatives thereof and (iii) dicyclopentadiene or derivatives thereof at a (B)/(A) molar ratio within the range of from 0.8 to 1.2, and (II) reacting the resultant reaction product with (C) at least one compound selected from the group consisting of .alpha.,.omega.-polybutadiene glycol and .alpha.,.omega.-hydrogenated polybutadiene glycol. A polybutadiene-modified unsaturated polyester comprising said polybutadiene-modified unsaturated polyester and a polymerizable monomer possessing at least one double bond.

Abstract: An unsaturated polyester resin composition for coating metal substrates, comprising an unsaturated alkyd component and a polymerizable vinyl monomer, said unsaturated alkyd component selected from the group consisting of:(a) compounds resulting from addition of mono-epoxy compounds possessing a .beta.,.gamma.-unsaturated ether to the carboxyl group of dicyclopentadiene-modified unsaturated alkyds, and(b) mixtures of dicyclopentadiene-modified unsaturated alkyds with unsaturated alkyds obtained by the ring-opening copolymerization of .alpha.,.beta.-unsaturated dicarboxylic anhydrides and mono-epoxy compounds possessing a .beta., .gamma.-unsaturated ether group.