Preparation of elastic branched copolyester for toner binder: Effects of branching agents

The branched copolyester was synthesized and its molecular weight, T _g, 1/2 method temperature (T _1/2) and rheological properties were characterized for the application of toner binder. The linear copolyester had low molecular weight and melt elasticity obtained by dimethylterephthalate (DMT), ethylene glycol (EG) and 2,2-bis(4-(2- hydroxypropoxy)phenyl)propane (HPP). The branched copolyesters prepared with various branching agents such as 2(hydroxymethyl)-2-ethylpropane-1,3-diol (trimethylol propane, TMP), 2,2-bi(hydroxymethyl)1,3-propanediol (pentaerythritol, PER), 1,2,4-benzenetricarboxylic anhydride (trimellitic anhydride, TMA) and glycerol to improve the physical properties of the linear copolyester. The effect of branching agents on the molecular weight and melt elasticity of the branched copolyester was examined. The branched copolyesters prepared by adding over 15 mol% of branching agent showed relatively high molecular weight and melt elasticity, and T _1/2 value of 140°C. Therefore, the highly branched copolyesters were deemed suitable as a hot-melt toner of laser print process.