(1) Definition
The size range of powder coating particles and the proportions of particles of various sizes in the total amount are called particle size distribution.
(2) Equipment
The size and aperture of the sieve should comply with the requirements of GB6003-85 "Test Sieve". It is recommended to use a circular sieve with a diameter of 200mm and a depth of 50mm. The aperture and quantity of the sieve should be selected according to the requirements.
The sense of industrial balance is 0.5g.
Seal screen lid, catch pan and soft bristle brush.
(3) Test procedure
Weigh out 100g soil and 0.5g powder sample, which can be sieved by stacked sieve or single sieve.
①Stacked sieve screening The selected group of sieves are stacked up and down according to the order of aperture size, and the smallest aperture is at the bottom. The powder sample is poured into the top sieve.
②Single sieve: Pour the powder into the selected sieve with the smallest aperture for sieving, and then pour the leftovers into a sieve with a larger aperture for sieving, and proceed until all the sieves are used.
The stacked sieve or single sieve is equipped with a feeding tray, and the cover is placed on it. It can be held with one hand during screening, if it is too heavy, it can be installed on the cantilever hanger, and the screen surface should maintain an inclination angle of 10'~2 ore. Lift the sieve lightly by hand, about 120 times per minute, place the sieve in a horizontal position after every 30 times, turn the 90' angle and re-pat the sieve frame with your hands or give periodic vertical vibration, or shake it by hand. If the powder is not easy to sieve out, you can lightly brush the bottom of the screen with a brush to help the powder fall.
The sieving time should be determined through experiments according to the size of the powder type and the sieving method. When the penetration of the powder within 1 minute is less than 1% of the feeding amount, it will be used as the end point of the sieving. After sieving, the sieve or pan and the powder in it can be weighed together, and then the mass of the sieve or pan itself can be subtracted; the powder sample can also be taken out and weighed separately, but care should be taken to brush off the adhering powder.
(4) Results
Calculate the percentage of the amount of remaining powder on each sieve to the total powder sample, and indicate the loss percentage of the stacked mass (including the powder weight in the pan). The loss should not exceed 2%, otherwise the weighing process should be carefully checked and re-tested if necessary.
