In recent years, due to the advantages of near-zero VOC emissions, powder coatings have become a rapidly developing field in the entire coating and coating industry, and its rapid development has been driven by the current national green environmental protection and sustainable development.
China has gradually become the world's main production base for stoves, ovens, exhaust pipes, etc., and the market demand for high-temperature and heat-resistant powder coatings is growing.
The so-called high-temperature and heat-resistant powder coatings refer to powder coatings that can withstand temperatures above 300°C for a long time without being damaged, and can still maintain appropriate mechanical properties and play a protective role, and the color change range and gloss loss of the coating are within the agreed range.
According to the heat-resistant properties and technical characteristics of the coating, heat-resistant powder coatings can be divided into ordinary heat-resistant and high-heat-resistant types. The appearance of ordinary heat-resistant powder coatings can be flat, sand-textured, and hammer-textured, and the heat-resistant temperature is lower than 300°C;
The temperature of high-heat-resistant powder coatings can reach above 400°C. Due to the particularity of the raw materials, silicone resin is generally required to participate in the design of the formula, and the obtained products are all sand-textured products, and it is difficult to obtain flat and hammer-textured appearances.
Application fields and performance requirements
Heat-resistant powder coatings are widely used in power stations, power stations, metallurgy, petroleum, chemical industry, food and other fields, such as BBQ ovens, high-power lighting covers, heating pipes, hot air furnaces, ovens, motorcycle exhaust pipes, chimneys and other high-temperature resistant equipment. Taking BBQ ovens as an example, most of the substrates are cold-rolled steel plates, and a few are cast aluminum. Pre-treatments such as degreasing, rust removal, phosphating/passivation are used. After electrostatic spraying of heat-resistant powder coatings, the film is cured. The use temperature is between 200~300°C, and the peak temperature is 350°C.
The coating film not only needs to meet conventional performance requirements such as impact, hardness, bending, adhesion, acid and alkali resistance, aging, etc., but also needs to achieve certain thermal cycle performance, such as adhesion, color difference, gloss change before and after high-temperature quenching.
For example, the high-temperature resistant powder coating used for vehicle exhaust pipes can be used at a temperature of 350~550℃. Under high-temperature conditions, the coating film should not have appearance defects such as cracks, cracking, blistering, and powdering. The color difference value, gloss loss rate, etc. are agreed upon, and the color is mainly black.
