Applying different surface treatments on different plastic materials, examining the effect on paint test performance and developing a high-performance painting process

Abstract

Nowadays, the standard plastic part painting process which is used in the automotive industry today, consists of surface cleaning, surface pre-treatment, primer, base coat and clear coat applications. Although high performance engineering polymers have high mechanical & chemical properties and atmospheric resistance, their use in various applications is limited due to their low surface energies. For this reason, the research and development activities of surface pretreatment applications that increase the surface wetting ability in the automotive industry have increased significantly in recent years. Flame, mechanical and chemical etching, corona and plasma application methods are among the actively used and newly developed surface activation processes. In this study, test plates were prepared from polyamide (PA GF15), Acrylonitrile Butadiene Styrene (ABS), Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS), Polypropylene (PP TD10, PP TD17, Primerless PP) polymeric materials that are used in the automotive industry. Various variations of surface pre-treatment, primer, base coat and clear coat were applied to the test plates. These variations were divided by two categories as related to surface pretreatment and primer application.Three different methods were used for surface pretreatment; (1) flame application, (2) atmospheric plasma application, (3) no surface pretreatment application. There are two conditions for primer application; (1) primer application, (2) no primer application. Application distance was determined as a variable parameter in surface pretreatment methods. Other process parameters were kept constant. This application distance was defined as 10 and 20 cm for flame application, 7 and 10 mm for atmospheric plasma application. After each surface treatment, the surface wetting abilities were analyzed by contact angle measurement and the both morphological and roughness paramter change on the surface were examined with scanning electron microscope (SEM) and 3D optical microscope device. The effect of both surface pretreatments and primer applications on paint performance tests was analyzed. Examined paint performance tests were adhesion resistance, water resistance, humidity resistant, thermal cycle resistance, impact resistance and stone impact resistance. The results of these paint performance tests were evaluated for each material as separately and the optimum painting process steps were determined as special to each polymeric material.