ポリプロピレン表面の塗装のための表面処理方法

抄録

The improvement of polypropylene surfaces by means of fluorine gas was investigated. It was found that polypropylene surfaces treated with fluorine gas diluted with nitrogen became hydrophilic. The optimum fluorination condition was a fluorine concentration of 0.5-1.0% and treatment times of 1-10 minutes. Hydrophilic properties were evaluated by contact angle. The polar-force component and dispersion-force component in surface free energy were calculated from contact angle using water and methylene diiodide. In particular, the lower polar-force component increased from 1.6mJ/m² to 25.0mJ/m². ESCA data showed that -CF-CF- and -C-CF- bondings formed on the upper surface. It has thus been demonstrated that these C-F bondings are given polarity by the fluorine which is the strongest electronegativity. The hydrophilic properties are thought to be due to this polarity. Adhesive strength was tested by cross-cut test with the hydrophilic surface coated with urethan paint. The painting exhibited good results. The high adhesion strength is thought to be the result of polar interaction. It is clear that good coating can be obtained by treating polypropylene surfaces with fluorine gas.