Shanghai wax powder manufacturers take you to understand the application characteristics of fast curing polyester in powder coating:
For fast-curing powder coatings, the traditional concept is that it is easy to achieve rapid curing by adding a curing accelerator to the design of the powder coating formulation; however, excessive dependence on the additives often leads to other undesirable diseases, such as: poor leveling , baking yellowing and fading, powder thermal storage performance and so on. In this paper, based on the actual construction conditions of low-temperature curing texture and plane powder, conventional sand wrinkle powder, thermal transfer powder, etc., the apparent performance, mechanical properties and thermal storage stability of the powder are combined to demonstrate different reactive polymerization. The choice of esters affects various performance indicators and ultimately proposes a total solution.
Fast-curing polyesters often have the following benefits in the following aspects of the use of powder coatings. For example: (1) increase the crosslink density, thereby improving the mechanical properties such as film hardness, cross-hatch adhesion, impact resistance; (2) reducing the curing temperature or shortening the curing time to achieve low-temperature curing or rapid curing; It hinders the melt leveling of the powder, and achieves the apparent control of the size and the three-dimensional texture of the texture; (4) interspersed with the slow or medium-speed curing system, and achieves the reduction of the surface sightseeing while leveling. However, while the fast-curing polyester has gained the above advantages, other disadvantages are gradually revealed. For example: (1) poor thermal storage stability, the resulting powder coating is easy to agglomerate; (2) the coating film has poor leveling performance, and orange peel is easy to appear. To this end, a successful fast-curing polyester product must balance the two pairs of contradictory indicators such as mechanical properties and leveling performance, heat storage stability and curing conditions. In order to apply the different types of powder coatings, the fast curing polyesters have different emphasis on the above indicators in the R&D and production engineering; therefore, the classification is different and the use characteristics are also different. The following describes the major types of fast curing polyesters and their corresponding use characteristics.
2. Application of fast curing polyester in thermal transfer powder coating
The difficulty in thermal transfer type powder coatings has always been the problem of tearing paper. If the tearing effect is good, there is no print mark or less print mark, and the transfer production efficiency is high; if the paper or the paper is not torn, the print mark is obvious and the production efficiency is low. After many experiments, the results show that the factors affecting the transfer film tearing are mainly: (1) the hardness of the coating film, the higher the hardness, the better the tearing of the paper; (2) the complete degree of curing of the polyester, the faster the curing speed The more complete, the better the tearing of the tearing paper; (3) the distribution of the molecular weight of the polyester, the larger the molecular weight, and the narrower the distribution, the better the tearing of the tearing paper.