High Water‐Resistance Conductive Waterborne Polyurethane Coating for Broadband Electromagnetic Interference Shielding

ABSTRACT Conductive water‐based coatings were prepared using waterborne polyurethane as the matrix and silver‐coated glass powder as the conductive filler. The waterborne polyurethane coating with excellent water resistance was prepared by adjusting the molar ratio of isophorone diisocyanate to polypropylene oxide glycol, using dimethylol propionic acid as the chain extender and 2‐hydroxyethyl acrylate as the end‐capping agent with the photocuring reaction during the curing process. The variation in tensile strength of waterborne polyurethane coating films with formulation adjustments was analyzed via molecular dynamics simulations, and the adhesion to wood substrates exceeded 5 MPa. When the dosage of silver‐coated glass powder was 3.5 times the solid content of the waterborne polyurethane emulsion, the water absorption rate and volume resistivity were less than 2% and 1000 Ω·cm, the adhesion strength and pencil hardness reached 0.5 MPa and 3H, and the electromagnetic interference shielding effectiveness exceeded 50 dB in the frequency range of 100 MHz–10 GHz.