The application of powder coating in aluminum profile spraying

Since the emergence of powder coatings in the early 1970s, powder coatings have received widespread attention worldwide due to their complete solvent-free conversion into coatings, high coating efficiency, good comprehensive protective and decorative properties, and other advantages. As a result, metal profiles have been widely used in various aspects of buildings due to their excellent durability, decorative properties, and processing formability. Aluminum profiles account for more than 80% of metal profiles due to their excellent processing performance, light weight, and other characteristics. The application of powder coatings in aluminum profiles has grown rapidly. Currently, the application of powder coatings in aluminum profiles has expanded from Europe to the Americas, Australia, the Far East, the Middle East, and Africa
At present, there are generally three surface treatment methods for aluminum profiles: anodizing, electrophoretic coating, and powder spraying, each of which has its own advantages and occupies a considerable market share. In the coating of aluminum profiles, representative types of powder coatings include epoxy, polyester, acrylic, and organic silicone resin powder coatings. As applications, high corrosion-resistant aluminum profiles such as some aluminum frames, doors and windows, balconies, corridors, and partition panels are mostly coated with polyester and acrylic powder coatings. In addition, due to the excellent adhesion and corrosion resistance of epoxy resin powder coatings, but poor weather resistance, they are generally used indoors or as primers
2. Manufacturing types and properties of aluminum profile powder coatings
At present, the powder coating commonly used in aluminum profiles is weather resistant polyester powder coating. Most of the polyester resins used in powder coatings are saturated, and we usually divide them into two categories based on their end group structure: carboxyl end group and hydroxyl end group.
The number average molecular weight of carboxyl terminated polyester ranges from 2000 to 8000, and the acid value ranges from 20-100mg KOH/g. Among them, medium and high acid values (45-85) are generally used in epoxy/polyester hybrid powder coatings, while low medium acid values (20-45) polyester is prepared with isocyanurate triglyceride (TGIC) and hydroxylamine as curing agents to prepare weather resistant pure polyester powder coatings.
The weather resistance of polyester/TGIC powder coatings can be classified into three categories based on the Florida sun exposure test results:
1) Standard weather resistant powder coating (can pass Florida exposure test standard 1-2 years)
2) Improved weather resistant powder coating (can pass Florida exposure test standard for 2-3 years)
3) Ultra weather resistant powder coating (can pass Florida exposure test standard for more than 5 years)