Synthesis And Modification Of Hyperbranched Polyesters Used As Solvent-free Coatings

With people’s environmental awareness are waked gradually, high solids andsolvent-free coatings have been the most important coatings in the future. The hyperbranchedpolymers （HBPs） display low viscosities, high solubility and active end groups, and would beused in a high solids and solvent-free coatings. The viscosities of present HBPs are usuallytoo large and its coating film have some defects including slow drying and low hardness. Sothe novel hyperbranched polyesters were synthesized by using ethoxylated polyol as coremonomers and DMPA as an AB2monomer as well as the pseudo-step method in this paper.The structures, molecular weight and intrinsic viscosities of HBPs are measured with fouriertransform infrared spectroscopy （FT-IR）, gel permeation chromatography （GPC） and1H-NMR spectroscopy （1H-NMR）. And then those HBPs were modified with ether and-caprolactone and their film properties cured by the toluene diisocyanate adduct were tested.In the end, the novel with terminal hydroxyl groups was synthesized and the properties of themixed HBPs with reactive diluents were investigated. The conclusions are as follows:（1） The hyperbranched polyesters synthesized with ethoxylated polyol as a core moleculeexhibit a viscous liquid at room temperature. The degree of branching of HBPs is in the rangeof0.44-0.48. The molecular weight of HBPs is ranged from1800to3000with1.60-2.15ofthe molecular weight distribution index. The intrinsic viscosities of HBPs is up to3.85and5.51mL·g^-1. HBPs were soluble in acetone, ethanol and DMF, while insoluble in benzene,toluene and xylene. These HBP films possess excellent flexibility and thermal stability.（2） The second generation hyperbranched polyester with TMP or PE as the core weresynthesized and modified with ether and caprolactone. The molecular weights of HBPs are inthe range of1600-3400with1.97-2.52of the weight distribution index. The intrinsicviscosities of HBPs are between0.95and2.89mL·g^-1. The crosslinked film exhibitedexcellent properties including2H of the hardness,1class of the adhesion, and1mm of theflexibility. It also found that the second-generation modified hyperbranched polyester withTMP as the core monomer displayed optimum film properties with6:6of the molar ratio ofcaprolactone and benzyl ether, and the corresponding ratio is6:10for PE as the core monomers.（3） The novel reactive diluents with terminal hydroxyl groups were synthesized withpolyol,-caprolactone and ether as the materials. Its viscosity is low to360mpa·s. When thereactive diluents blends with HBP-3resin by the mass ratio of6:4, the viscosity of mixturewas4200mpa·s, which meeting the performance and application requirements forsolvent-free coatings. The optimal formulation of two-component polyurethane coatings freesolvent was obtained with9/1of the mass ratio of G21and G18and1/0.9of the molar ratio ofNCO and OH.