company news about How to improve the leveling performance of powder coatings

How to improve the leveling performance of powder coatings? Powder coating is a new type of solvent-free 100% solid powder coating. Powder coating is made up of resin, pigments, curing agents, and other additives mixed in a certain proportion, and then prepared through processes such as hot extrusion, crushing, and sieving. At room temperature, it is stored stably and subjected to electrostatic spraying or fluidized bed immersion coating, followed by heating, baking, melting and solidification to form a flat and bright permanent coating film, achieving the purpose of decoration and corrosion prevention.
Leveling refers to the flat and smooth state of the coating film after coating application. A surface with good leveling should have no irregular shapes such as orange peel, brush marks, ripples, shrinkage holes, etc.
The factors that affect the leveling performance of powder coatings mainly include three aspects:
1、 Leveling agent: Add appropriate leveling agent to the formula of powder coating, such as Tianshi TWAX-988 powder coating wax micro powder, high melting point, smooth hand feel, good fluidity, easy dispersion, and ultra-fine particle size; Less addition, reducing costs and increasing efficiency; Improve the powder loading rate of silver powder.
2、 Melt viscosity of powder coatings: For thermosetting powder coatings, during the melt flow process, there is a cross-linking curing reaction. The higher the temperature, the faster the curing reaction, the faster the system viscosity increases, the shorter the flow time, and the leveling performance is restricted. Therefore, the melt viscosity of powder coatings cannot accurately reflect the final leveling of the coating film, and the effects of baking process, heating rate, crosslinking curing temperature, etc. on the leveling of the coating film must be considered simultaneously.
3、 Baking process: After powder coating, there is a heating process during baking, and the speed of heating has a considerable impact on the leveling of the coating. Under different heating rates, the trend of dynamic viscosity changing with temperature is basically consistent, that is, the viscosity initially decreases with the increase of temperature and reaches the minimum value, and then increases with the increase of temperature, which is caused by cross-linking reaction. More importantly, the faster the heating rate, the smaller the minimum viscosity, and the higher the corresponding temperature, which is more conducive to the curing and leveling of the coating.
The leveling performance of powder coatings is limited by the structure and curing mechanism of leveling agents and film-forming resins. By using appropriate leveling agents, selecting low melt viscosity resin systems, and matching curing processes, excellent leveling performance coatings can be obtained. The application of wax micro powder in powder coatings can also have a bonding effect. Ultra fine wax powder does not dissolve at a bonding temperature and can be coated on powder coating particles to prevent adhesion. Compared to inorganic materials, wax powder as a bonding agent will not have adverse effects on the leveling of powder coatings.