The selection element of the thermoo-solid powder coating raw material

China Coatings Online News Information:
thermostate powder coating is composed of resins, curing agents, pigments, fillers and other additives. It is important to choose these raw materials because of their significant impact on coating quality and coating performance.
1, resin selection
resin structure and performance is the main factors that determine the quality of powder coating and coating performance, should have the following basic technical requirements:
thermoo-solid powder coating resin must contain active function groups to ensure the formation of a mesh structure when baking into a film.
in the powder coating construction process, if the decomposition temperature of the resin and melting temperature is very close, it is very difficult to control the heating temperature. Therefore, the temperature difference between the melting temperature and the decomposition temperature of the resin is required to be large.
the resin melting viscosity is low, narrow range, when reaching the melting point above the temperature, the viscosity should be rapidly reduced. In this way, with powder coating electrostitectral spraying, fluidized bed immersion and other methods of coating on the coating can get a better leveling coating.
coatings that have been sprayed in powder coatings can be recycled and re-used. However, some powder particles have been in contact with air for a long time, because of the influence of moisture and temperature changes, so the physical and chemical stability of the resin is better.
powder coatings are generally produced by mechanical crushing, resulting in uniform particle size distribution and particle shape. The resin should choose a higher glassing temperature and melting point to make it more crushing.
the adhesion of the powder coating is a key role to be played by resin. If the binding force of the coating is good, there is no need to apply primer, and the durability of the coating film is also good. Thermoplastic resins have poor adhesion, so pre-coat the primer.
requires the resin to be light, transparent and non-toxic.
2, curing agent selection
curing agent is an important factor of resin modified and film-forming, it directly affects the quality of powder coating and coating performance. Therefore, it is important to choose the right curing agent, which should have the following conditions:
1. At room temperature is powdery, granular or flaky.
2. Chemical and physical stability: no chemical reactions with resins or other compositions during production or storage, no reunion of lumps. When spraying construction, baking to a given temperature can be quickly cured, coating film flat, smooth, plump.
3. Curing agent should be non-toxic (low toxic), non-irritating, in the process of baking into film, it is best not to release odors and harmful odors.
4. The curing agent is colorless and cannot color the coating film and affect the appearance of the coating film.
3, pigment selection
pigments and fillers in powder coating components in the production preparation and storage process can not be chemically reacted with other components, the stability of heat and light is better. Pigments used in powder coatings should meet the following conditions:
1. Can be evenly dispersed in the resin.
2. The thermal stability is good when the coating film is cured.
3. Light stability, chemical resistance, solvent resistance is good.
4. No permeation, no frost, no migration in the coating film.
5. Color does not change depending on other parts.
does not cause the resin to age.
7. In the hot melting state of resin, the dispersion is good.
8. Good coloring and covering.
4, filler selection
adding fillers to powder coating formulations also has a modified effect, such as adjusting coating flatness, gloss and physical mechanical properties. The selection requirements for fillers are:
1. Easy to disperse in formula parts, good liquidity.
2. Contains no foreign impurities that affect the quality of the coating film.
3. No harmful chemical reactions occur with other compositions.
4. Does not reduce the physical and mechanical properties of the coating film.
5. Does not reduce the physical and mechanical properties of the coating film.
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