A plastic powder coating is a method in which a powder material is applied to a surface of a substrate and heated to a fluid state, and then cured to cover the surface of the substrate to form a protective or decorative coating. Powder coatings have many advantages over traditional liquid coatings, such as better environmental performance, a thicker coating in one coat, and a variety of styles.
Powder coating is still complicated in some aspects, and it is necessary to select the appropriate product and coating process according to different needs. So how do you do the powder coating?
1, the steps of powder coating
1.1 First determine the type of substrate that needs to be painted. Powder coatings are divided into two types, thermoplastic and thermosetting. It is necessary to select a suitable powder coating according to different substrates to achieve the best coating effect.
1.2 Disassemble all threads or lubrication connections and all parts that do not need to be painted before painting begins. It sounds simple, but many people forget this step. Powder coatings adhere to everything, including screws, nuts, bearings, etc. that do not need to be painted.
1.3 Thoroughly clean the metal surface. The cemented carbide is treated by shot blasting or sand blasting to remove dirt and rust from the surface. The surface grease and coating are cleaned with a chemical solvent and can be polished. If necessary, aluminum, magnesium and other soft metal alloys can be cleaned with a solvent and brushed with a wire brush.
1.4 Apply the powder coating to the surface of the substrate. By using a spray gun or compressed air sprayer to apply a charged powder coating to the grounded substrate surface, the price of the gun is recommended to be as low as $100, depending on the supplier. In the experiment, the powder can be sprayed directly onto the surface of the metal sheet.
1.5 Select the appropriate temperature to cure the powder coating attached to the substrate. The oven can be used for curing, generally for metal substrates of relatively small size, and large substrates can also be cured by infrared or other flameless heat sources. Typically, the object is heated to 175 to 190 ° C for about 10 to 15 minutes and then cooled.
2. The difference between thermoplastic powder coating and thermosetting powder coating
2.1 The thermoplastic powder coating can be remelted and solidified, and the coating of the thermosetting powder coating can hardly be remelted and solidified after curing, which is the most obvious difference between the two.
As the name suggests, thermosetting powder coatings cannot be re-solidified because of irreversible chemical reactions. In contrast, thermoplastic powder coatings do not undergo chemical reactions during curing.
2.2 Which coating to choose depends on the characteristics of the substrate to be coated. Thermoplastic and thermosetting powder coatings are used on different substrates due to their different chemical properties.
Thermosetting powder coatings: Reinforces the integrity of the substrate, is suitable for substrates that can be severely worn, and provides chemical and thermal resistance.
Thermoplastic powder coatings: provide strength and flexibility, commonly used in plastics and mechanical parts.
2.3 About the advantages and disadvantages of thermosetting powder coatings. Generally thermosetting powder coatings are used on heat resistant substrates.
Advantages: beautiful coating; low cost; good coating stability and heat resistance.
Disadvantages: The irreversible curing process means that the coating cannot be recycled and it is difficult to melt and cure twice.
2.4 About the advantages and disadvantages of thermoplastic powder coatings. Thermoplastic powder coatings are commonly used on plasticity and durability substrates like park benches, and are also used extensively on the outer surface of metal pipes.
Advantages: high lubricity; ability to remelt and cure; increase impact resistance
Disadvantages: Generally speaking, the cost is high; heating may melt.