| 摘要 |
PURPOSE:To realize the cleaning in a short process without using any organic solvent for cleaning, before coating, a plastic bumper molded particularly by using zinc stearate as an internal mold release agent. CONSTITUTION:This process comprises the steps of: cleaning a polypropylene and/or polyurethane bumper at 60-80 deg.C with an acidic aqueous cleaning solution which has a pH of 2 to 4 and contains a mineral acid in an amount of 0.1-100g/l, a fluorine compound in an amount of 0.01-10g/l, a nonionic surfactant with an HLB of 12 to 16 in an amount of 0.1-10g/l, a polyethylene polypropylene derivative foam inhibitor with an HLB of 6 or lower in an amount sufficient to provide a weight ratio of this foam inhibitor to the nonionic surfactant of (0.1 to 2):1, and a sodium and/or ammonium pH regulator; washing the cleaning solution with water and blowing it away by air; and drying at room temperature to 80 deg.C. |
