Preparation of aluminium metallic pigmented powder coatings with high color stability using a novel method: Microwave bonding

This paper focuses on the preparation of metallic pigmented powder coatings with high color stability via a self-designed microwave bonding device. With the increasing environmental regulation on the use of traditional metallic paint, there has been a corresponding interest in metallic pigmented powder coating, owing to its zero VOCs emission, high protective property as well as sparkling aesthetic appearance. metallic pigmented powder coatings are mainly composed of two non-compatible ingredients: base powder coating(s) and metallic pigment(s). Bonding the two kinds of materials together is an effective approach to eliminate their non-compatibility problem and ensure color stability. Here, a self-designed bonding device based on microwave heating was invented to bond metallic pigmented powder coatings. Furthermore, a direct and quantitative characterization method, ash test, was first used to reveal the bonding quality by analyzing the mass percentage of metallic pigment in the powders. A comprehensive investigation on non-bonded powder was performed as a control test. The microwave-bonded samples were prepared with the device at various temperatures and rotating speeds followed by evaluation with ash test. After microwave treatment, reliable bonding of base powder coating and metallic pigment were proved via a series of characterizations, such as ash test, SEM, EDS, optical observation and size analysis. Therefore, the microwave bonding method is trusted to be a feasible and effective production method of metallic pigmented powder coatings.