Composition of powder coatings
Composition of powder coating
Powder coatings are organic coatings composed of dry, solid (doesn’t contain solvents).The base formula of powders is composed of different materials : resin, hardener, filler, pigment and additives.
For powder coatings nowadays two types of resins are used : thermoplastics or thermosettings.
- Thermoplastic powders:These powders (e.g. polyethylene, PVC, …) will melt and flow together to one layer (the coating) when applying. If this coating is heated up afterwards the layer will become weak.
- Thermosetting powders: The coating will melt on temperatures between 150 and 200°C, and will flow out and cure. These coatings will not become weak if they are exposed to high temperatures. The most common thermosetting powders are composed of one or more of the following resins : epoxy, polyester, polyester-urethane, acrylate.
The hardener is one of the most important ingredients of powder formula. The hardener is responsible for the curing of the powder and dictates, in conjunction with the resin, the specific properties of the coating : chemical resistance, thermal stability, physical and mechanical characteristics.
Pigments are used to give colour.There are organic as well as inorganic pigments. Depending on the application, a choice is made between light fast, food-contact safe or temperature stable pigments.
Fillers in powder coatings are used to contribute positively and technically to the system. This can be : a. to resist sagging out of the film b. to improve abrasion resistance c. to improve resistance to humidity