The significance of particle size distribution analsis for powder coating
laser particle size analyzer test results:
Average particle size (median diameter), the boundary of particle size and particle size distribution of the dispersion.
- The average size of the sample is less than and greater than 50% of particles.
- The boundary particle size: closer to the common sense to the maximum and minimum particle size. However, the maximum and minimum particle size to describe the upper and lower limits of the sample particle size unscientific, it is generally the boundary particle size, such as (D10, D90) = (8,60), it represents less than 8 microns in diameter particles accounted for 10% and 90%, the number of particles smaller than 60 microns in diameter.
- The dispersion of particle size distribution = (D90-D10) / D50, dispersion, the smaller the particle size distribution is more narrow, too big and too small number of particles in the smaller particle size the higher the concentration.
The relationship between particle size and powder quality:
Particle size distribution and the film texture, smoothness, gloss, the effect of the particle, live results, powder fluidization, storage stability and powder recovery rate is closely related.
- Appearance, leveling, and the particle: In general, the smaller the powder particle size, the better the smoothness in the paint curing; the same coating thickness, the small particle size of the powder is not easy to appear particle; the appearance of the coating is more smooth, smooth.
- live effects and flour yield:Charged to improve the powder particles, the powder coating of powder on the rate will be increased. The main adsorption force of the electrostatic spraying electrostatic powder, flour yield depends on the amount of the charged powder particles. Powder with the power and powder particle size is proportional to the square. Increase the particle size, powder with higher consumption, the powder rate. Powder particle size is too large, too large particle size, the gravity of the large particle powder over aerodynamic and electrostatic powder coating during the flight, has been falling due to gravity does not reach the surface, but to make the powder rate. Powder too fine charged lower coating application efficiency will drop, ultra-fine powder (particle size <10μm) basically do not live at the same time the powder is too fine also increased the difficulty of powder production.
- The powder flow effect:The powder are too small, too small powder will bear the integrated powder regiment, streaming will not spread. When sprayed onto the workpiece to form a sleek and small, affect coating appearance. When the powder is too coarse powder for the powder barrel is not easy fluidization.
- The storage stability:Stability refers to the powder coating under certain conditions, to keep the powder particle size, shape and hardness capability, ie, whether the powder in the storage or use will absorb moisture, the occurrence of phenomena such as powder caking. Usually more fine powder, especially the ultrafine powder content of less than 10μm too much powder easy to absorb moisture, knot groups, decreased stability, will plug the gun, spit powder bad.
- The recovery rate:Powder coating production plant and powder coating paint plant there is the issue of recycling powder coating, usually, the powder particle size <10μm ultra-fine powder recovery rate is low, when the powder particle size> 10μm pm powder coating recovery rate rising rapidly, and the powder The recovery rate increased as the particle size increases.
Powder coating to do the significance of the particle size detection is the same formula, the guidance of powder production, the performance of the powder to achieve maximum optimization.