Thermosetting powder coating is composed of resin, curing agent, pigment, filler, and other additives. Choosing these raw materials is very important because they have a significant impact on the quality of their coatings and the performance of their coatings.

一、 Selection of resin

The structure and properties of resin are the main factors determining the quality and coating performance of powder coatings, and should meet the following basic technical requirements:

1. The resin used for thermosetting powder coatings must contain active functional groups to ensure the formation of a network structure during baking and film formation.

2. During the construction process of thermosetting powder coatings, it is very difficult to control the heating temperature if the decomposition temperature and melting temperature of the resin are very close. Therefore, it is required that the temperature difference between the melting temperature and decomposition temperature of the resin be large.

3. The resin is required to have a low melting viscosity and a narrow range. When reaching a temperature above the melting point, the viscosity should rapidly decrease. By using methods such as powder coating electrostatic spraying and fluidized bed immersion coating, a coating with good leveling properties can be obtained on the coated material.

4. Coatings overspray in powder coatings can be recycled and reused. But some powder particles may change after prolonged contact with air due to moisture and temperature, so the physical and chemical stability of the resin is better.

5. The production of powder coatings generally adopts mechanical crushing method, which can obtain uniform particle size distribution and particle shape. Resin should have a higher glass transition temperature and melting point to achieve better pulverizability.

6. The adhesion of powder coatings relies heavily on resin. If the adhesion of the coated material is good, there is no need to apply primer, and the durability of the coating film is also good. Thermoplastic resin has poor adhesion, so it needs to be pre coated with primer.

7. Require the resin to be light in color, transparent, and non-toxic.

二、 Selection of curing agent

Curing agent is an important factor in resin modification and film formation, which directly affects the quality and coating performance of powder coatings. Therefore, selecting the appropriate curing agent is crucial, as it should meet the following conditions:

At room temperature, it is in powder, granular or flake form.

2. Has chemical and physical stability: does not undergo chemical reactions with resins or other components during production or storage, and does not agglomerate or clump. When spraying construction, it can quickly cure after baking to a given temperature, and the coating film is flat, smooth, and full.

3. The curing agent should be non-toxic (low toxicity), non irritating, and preferably not release any odors or harmful odors during the baking and film-forming process.

4. The curing agent is colorless and cannot color or affect the appearance of the coating.

三、 Selection of pigments