抄録
This paper describes the research on etching mechanism for coating of polypropylene resin. After pre-etching with xylene and etching with chromic-sulfuric acid mixture at 60°C, the resin was examined by weight loss, surface roughness, and crystallinity.
The results of experiments were summarized as follows:
(1) The weight loss by etching increased with the progress of pre-etching time. It was believed that the degree of swelling of the resin surface and the dissolution of small molecules from the surface increased with the increase of pre-etching time. The results revealed that the resin surface was more easily etched by the subsequet acid etching.
(2) In the standard type of polypropylene resin, the curve representing the relation between surface roughness and etching time was found to show a maximum roughness, but the same curve in the plating type of polypropylene resin was found to be linear.
(3) No carbonyl radicals were formed on the resin surface layer etched under the same conditions.
(4) Crystallinity of the resin was reduced by etching, which was assumed to be owing to the cutting of principal chains of crystalline molecules and their dissolution by etching.
(5) The adhesion of the standard type of polypropylene resin was poor owing to the effects of blisters and skips.
(6) The adhesion of the plating type of polypropylene resin increased during the first 60 minutes, and then, decreased with the lapse of time.
