METHOD FOR WASHING PLASTIC BUMPER

PURPOSE:To simply wash a plastic bumper without using any solvents by preliminarily washing the plastic bumper with hot water having a temperature not lower than the melting point of paraffin wax used for polyurethane bumper and then washing the bumper with a specific acidic and aqueous cleaning agent under specific conditions. CONSTITUTION:This method for washing a plastic bumper is carried out by preliminarily washing a polyurethane plastic bumper with a paraffin wax-based external mold release agent having >=90 deg.C melting point and a hot water having a temperature not lower than the melting point of the paraffin wax, and then washing the bumper with an acidic aqueous cleaning agent having pH2-4 at 60-80 deg.C, washing with water and blowing with air and drying the bumper from room temperature to 80 deg.C. The acidic and aqueous cleaning agent contains (A) 0.1-100g/l of a mineral acid, (B) 0.01-10g/l of a fluorine compound, (C) 0.1-10g/l of a nonionic surfactant having 13-17 HLB, (D) a polyethylenepolypropylene derivative defoaming agent having 0.1-2 mixed weight ratio to the component C and