Aqueous cationic polyurethane resin for transfer aluminum plating and preparation method thereof

The invention discloses aqueous cationic polyurethane resin for transfer aluminum plating and a preparation method thereof. The preparation method comprises the following steps of: reacting polyester polyol or polyether polyol with isocyanate to generate polyurethane prepolymer through prepolymerization; then performing chain extension, i.e., adding cationic hydrophilic chain extension monomer, increasing molecular weight of resin and introducing an ionizable group; and performing neutralization and emulsification to perform cationization on resin and then disperse in water. According to the invention, cationic polyurethane prepolymer is neutralized by using an acid, so that VOC (Volatile Organic Compound) problem of triethylamine is avoided, and no pollution and environmental friendliness are guaranteed; and by adjusting the proportion of soft segments to hard segments of polyurethane and adding a three-functionality chain extender, the stripping property and the heat resistance of the aqueous cationic polyurethane resin are improved.