The performance tests of powder coatings mainly include: angle of repose, outflow, apparent density, particle size distribution, softening temperature, gel time, melt fluidity, volatile matter content, storage stability, etc. This paper mainly introduces two methods of measuring the angle of repose and outflow.
1. Determination of angle of repose
(1) Measuring instruments (as shown in Figure 6-1) funnel, bucket frame, disc, protractor (connected frame) (related instruments: Viscosity Cup)
The mouth of the funnel should not be too large, preferably about 5 mm, and the size of the disc is not limited.
(2) Test method
Pour the loose powder to be tested into the funnel aggressively and flow to the back plate. Be careful not to pile up the powder in the funnel until the powder fills the plate and starts to flow out from the edge of the plate. At the same time, keep the angle a maximum, and then use a protractor to measure the value of a. Repeat 3 times and take the average value, which is the angle of repose. If the appearance of the accumulated powder is irregular, it can be measured according to the line connecting two points at the vertex and the edge of the disk.
2. Outflow determination
(1) Definition Flowability refers to the time for powder of specified quality to flow out from a specified funnel. (Related instrument: outFlow Cup)
(2) The test step should place the powder sample on the paper to make it loose and not knotted, and weigh out 100g
powder sample. Place the funnel vertically, seal its lower opening with a suitable slat, and gently pour the weighed powder sample into the funnel.
Quickly release the lower mouth and start the stopwatch at the same time, let the powder flow out by itself, stop timing when the powder stops flowing out.
