Characteristics of powder coating additives.
For fast curing powder coatings, the traditional concept is that the addition of curing accelerators can easily achieve the purpose of rapid solidification in the formulation of powder coatings. However, excessive dependence on additives often brings other bad criticism, such as flow adjustment, baking and fading, and poor thermal storage performance of powder. Based on the actual construction conditions of low temperature curing texture, plane powder, conventional sand wrinkle powder and heat transfer powder, the influence of the selection of different reactive active polyester on various performance indexes is demonstrated, and the overall solution is finally put forward. Plan.
Fast curing polyester is often used in powder coatings for the following aspects.
(1) increase crosslinking density and improve mechanical properties such as film hardness, lattice adhesion, impact resistance and so on.
(2) reduce curing temperature or shorten curing time to achieve low temperature curing or fast curing.
(3) obstruct the melt flow of powder and control the apparent size and texture of the powder.
(4) interacts with slow or medium speed curing systems to reduce apparent gloss while leveling.
However, the advantages of fast curing polyesters have been gained while other disadvantages have been gradually revealed.
(1) the stability of thermal storage is poor, and the powder coating is easy to cluster.
(2) film leveling performance is poor, it is easy to appear orange peel and so on.
To this end, a successful fast curing polyester product must balance the two contradictory indicators, such as mechanical properties and leveling performance, thermal storage stability and curing conditions. In order to apply different types of powder coatings, fast curing polyester has different emphasis on the above indexes in R & D and production engineering. Therefore, the classification is different and the use characteristics are different. Next, we will introduce several types of fast curing polyester and their corresponding usage characteristics.