▎ 摘　　要

NOVELTY - Preparation of modified aqueous polyurethane coating, involves (i) adding graphene oxide suspension and dopamine to water, uniformly mixing, adjusting pH to 8.5 with tris-chloride buffer solution, and reacting at a low temperature to obtain modified graphene suspension, (ii) evenly dispersing nano-silica and polyelectrolyte modifier in water, reacting at room temperature to obtain modified nano-silica, (iii) dispersing modified graphene suspension and modified nano-silica in aqueous polyurethane, mixing at high speed, and carrying out vacuum distillation to remove solvent. USE - Preparation of modified aqueous polyurethane coating for use as surface coating of plastics and metal plate. ADVANTAGE - The method enables simple, environmentally-friendly and easy preparation of modified aqueous polyurethane coating while reducing energy consumption, and makes graphene and nano-silica to disperse stably and uniformly in aqueous polyurethane coating, and this effectively avoiding the aggregation of nano-fillers and enables storage of composite modified coatings stably. By using surface-active groups and aqueous polyurethanes to form multiple cross-linked network structures, the composite modified coating is prepared with excellent hardness, salt water resistance, solvent resistance, thermal stability and excellent adhesion to coated substrates and excellent bonding strength. DETAILED DESCRIPTION - Preparation of modified aqueous polyurethane coating, involves (i) adding graphene oxide suspension and dopamine to water, uniformly mixing, adjusting pH to 8.5 with tris-chloride buffer solution, and reacting at a low temperature to obtain modified graphene suspension, (ii) evenly dispersing certain amount of nano-silica and polyelectrolyte modifier in water, reacting at room temperature to obtain modified nano-silica, (iii) dispersing modified graphene suspension and modified nano-silica in an aqueous polyurethane, mixing at high speed for a while at room temperature, then carrying out vacuum distillation to remove solvent, and obtaining composite modified aqueous polyurethane coating.