The second generation hyperbranched polyester (HBP-0) was synthesized by the pseudo-one step method with 2

2-bis (hydroxyl-methyl) propionic acid as AB2 monomer

trimethylolpropane as core monomer and p-toluene sulfonic acid as catalyst.HBP-0 was modified with ε-caprolactone and lauric acid to prepare modified hyperbranched polyesters (HBP-1

HBP-2

and HBP-3).The structure and molecular weight of HBPs were characterized by FT-IR

1H NMR and GPC.HBP-0 was synthesized with 0.43 degree of branching and its molecular weight approached the theoretical value and distribution factor was 1.72.The film properties of modified HBPs cured by toluene diisocyanate adduct were studied

and the results showed that the modified HBPs displayed excellent film properties in the gross

impact resistance

adhesion and flexibility.HBP-3 modified by both ε-caprolactone and lauric acid exhibited the best properties

including lowest viscosity up to 7500 mPa·s

surface drying time of 40 min and pencil hardness of F.While the corresponding data of HBP-1 and HBP-2 modified only by ε-caprolactone or lauric acid were 7×105 mPa·s

20 min and HB; 17500 mPa·s

90 min and 2B

respectively.