,本間 英夫 a, b ,高井 治 a, b a 関東学院大学 大学院工学研究科 (〒 236-8501 神奈川県横浜市金沢区六浦東 1-50-1) b 関東学院大学 材料・表面工学研究所 (〒 250-0042 神奈川県小田原市荻窪 1162-2) c 関東学院大学 総合研究推進機構 (〒 236-8501 神奈川県横浜市金沢区六浦東 1-50-1) d ㈱真工社 (〒 335-0032 埼玉県戸田市美女木東 2-2-6)Polyphenylene sulfide (PPS) , a heat-resistant crystalline polymer with a simple chemical construction, has a high melting point of about 280 ℃, outstanding chemical resistance, and noncombustibility established by an industry flammability test with no flame retardant chemicals. Furthermore, PPS is widely used in various fields based on its properties. When the PPS is plated, surface roughening is conventionally treated with a solution of hydrofluoric acid. However, the waste solution of this acid is difficult to treat correctly. It is therefore necessary to resolve this difficulty. This study investigated the plating process on PPS treated using atmospheric UV irradiation. High-quality electroless NiP plating was visually confirmed on the PPS resin surface by surface modification using atmospheric UV treatment. Adhesion strength of about 0.8 kN m -1 was obtained for the treatment. Therefore, plating on the PPS resins was possible after atmospheric UV irradiation, which is environmentally friendly.
High adhesion strength between Acrylonitrile Butadiene Styrene (ABS) plastic and plated metal has been conventionally obtained by chromic acid etching in manufacturing industry. However, in recent years, hexavalent chromium becomes the target as an environmental regulatory substances. Thus, the establishment of a chromium-free pretreatment method is expected. Electrolyzed sulfuric acid (ESA) is a unique oxidizer alternative to the chromic acid. Therefore, we have been trying to apply ESA to treat the surface of ABS plastic. Depending on the sulfuric acid concentration in ESA solution, modification effects such as changing the surface morphology and introducing the functional groups were different. The ESA in which the concentration of sulfuric acid is 75 wt% and 80 wt% can change ABS resin surface in quality to be hydrophilic from hydrophobic. Also, adhesion strength between plating metal film and the plastic was obtained maximum 1.2 kN/m. Mechanism of high adhesion was anchor effect with cohesion failure. Therefore, this environmentally friendly surface modification method is expected in industrial use.
A high-adhesion plating process for ABS resin was studied using a low concentration of ozone instead of using harmful hexavalent chromium. ABS resin can be modified by ultrafine, ozone-containing bubbles dispersed in water (<2 ppm). A high adhesion strength of approximately 1 kN/m was obtained when treated for 30 min. In contrast to the conventional etching processes containing hexavalent chromium, it is not necessary to apply a problematical wastewater treatment. Accordingly, this treatment could be used as a new sustainable technology in the near future.
Abstract:Plating on the plastic is one of the important technologies to decorate exterior automotive parts and electronic devices. Conventionally, etching solution contained carcinogen hexavalent chromium obtained high adhesion strength between metal film and plastic surface to decorative the plating. On the other hand, health damage and environmental pollution from waste etching solution are occurring. For the above reasons, development of chromium free pretreatment is an urgent problem to solve this issue. In this study, we concentrated the environmentally friendly surface modification process in which atmospheric UV treatment was used to investigate effect of surface morphology and state on the ABS (acrylonitrile butadiene styrene) plastic. As a result, morphology of ABS surface was kept smooth after UV irradiation treatment. The conversion from hydrophobic to hydrophilic on the ABS surface state was confirmed by contact angle test and FT-IR spectra. Moreover, it was confirmed that appropriate amount of oxidation was necessary for metal plating on the ABS plastic, in order to obtain high adhesion strength between metal film and plastics surface.
Mixture of chromic acid and sulfuric acid has been widely applied for hydrophilization of ABS resin. However, it is difficult to make the hydrophilic surface of PP resin, because chromic acid has poor oxidizing power for PP resin. In addition, due to environmental concerns, alternative technologies that do not use hexavalent chromium are required. The authors have confirmed that PP resin and ABS resin can be hydrophilized with electrolyzed sulfuric acid solution and then be plated to obtain enough adhesion strength in practical use. In this report, focusing on its hydrophilization behavior, we investigated the reason why hydrophilization is created, and assumed that hydrophilization is due to oxygen entering between bonds of carbon and hydrogen to become hydroxyl groups.
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