Highly branched and tartaric acid-based water-borne resins

In this study, water-borne polyurethane resins were produced using poly(pro pylene-ethylene) copolymer triol, toluene diisocyanate, and hydrophilic mon omers, dimethylol propionic acid and tartaric acid. The hydrophilic monomer s were used separately. In either case, the ratio of isocyanate functional groups to the sum of hydroxyl groups of polyol and hydrophilic monomer was kept constant. The increase in the amount of hydrophilic monomer increased the hardness of resins when used as varnish. Tartaric acid resulted in high er hardness than dimethylol propionic acid. The dispersions made by using t artaric acid had much larger particle sizes than those of dimethylol propio nic acid. In another set of experiments, the samples carrying the optimum p roperties from the two sets were mixed with methylol urea that served as cr osslinker in the baking step. The physical and mechanical properties were d etermined by changing the weight percentages of the two types of samples in the mixture, and by changing the methylol urea percentage of the mixture w hich exhibited the maximum hardness. All samples showed superior impact res istance, adhesion, and flexibility. (C) 2001 John Wiley & Sons, Inc.