Detection of apparent density of coating powder

The apparent density of powder coating powder is divided into loose density and packing density

1. Determination of bulk density

Apparent density test of powder coating with Figure 1

1. Scope and description

Bulk density is the density of the powder coating at rest, with voids between the powders.

2. Instruments and Materials

(1) The capacity of the measuring cup is (100±0.5)mL cylindrical cup, the inner diameter is (45±5)mm, it can be made of metal, and the inner surface is polished.

(2) The diameter of the opening at the bottom of the funnel is 33mm, made of metal, see Figure 4-1.

(3) The size and shape of the sealing plate shall be suitable for sealing the lower opening of the funnel.

(4) The sense of balance is 0.1g.

3. Measurement method

(1) Place the funnel vertically, its lower opening is directly above the measuring cup, the distance is 25-30mm, and the two are coaxial.

(2) Use a measuring cup to measure (115±5) mL of the loose powder sample, block the lower opening of the funnel with a sealing plate, and pour the sample into the funnel.

(3) Quickly release the sealing plate, let the sample fall into the measuring cup freely, scrape off the excess part of the top of the cup with a ruler, and do not vibrate.

(4) Use a balance to weigh the mass of the sample in the measuring cup, accurate to 0.1g.

4. Result representation

The loose density is calculated according to the following formula:

p=M/V

In the formula,

p——loose density of powder sample, g/mL;

M - the mass of the sample in the measuring cup, g;

V——The volume of the measuring cup, mL (100mL is specified).

Take the arithmetic mean of the two measurements.

5. Reference standard

National standard GB/T6554-2003, national standard GB/T5211.4-1985.

2. Determination of packing density

1. Scope and Description

Packing density is the density displayed when the powder is in a vibrating state from loose to dense packing state. Its size is not only affected by the type and amount of raw materials, but also related to the particle shape and particle size distribution of the coating.

2. Apparatus and Materials

(1) The diameter of the sieve is 200mm, and the aperture size is 0.4mm.

(2) The components of the filling volumetric device are as follows: Graduated cylinder, with a capacity of 250mL, equipped with a suitable sieve intervals of 2mL; graduated cylinder holder (with shaft), the total mass of graduated cylinder, stopper and graduated cylinder holder shall be (670 ± 45)g; The cam can raise the measuring cylinder seat frame every 1200 revolutions, and its vibration frequency is (250±15) times/min; the iron hub, the installation position should make the raised shaft end away from the iron hub (3±0. l) mm height falls on the Hu; the electronic counter calculates the vibration times of the measuring cylinder frame; the shaft sleeve is made of suitable materials to minimize the friction coefficient between the shaft sleeve and the shaft.

Apparent density test of powder coatings with Figure 2

See Figure 4-2 for the illustration of the instrument. There should not be too much free movement between the various parts of the instrument, and the friction between the sleeve and the shaft should be as small as possible without using lubricant.

(3) The constant temperature Drying Oven can be maintained at (105±2)"C.

(4) The sense of balance is 0.1g.

(5) The desiccant is equipped with an effective desiccant.

3. Measurement method

(1) Take about 500mL samples enough for two parallel determinations, dry them in a constant temperature Drying Oven at (105±2)°C for 2h, and then put them in a desiccator to cool to room temperature.

(2) Sieve the dried sample (aperture 0.4mm) to completely separate the aggregates, then weigh the sieved sample to about (200±l0)mL, accurate to 0.1g, and then It is added to the graduated cylinder filled with the volumetric device, and the cylinder is tilted and rotated about the axis while adding the sample, so as to avoid the formation of voids.

(3) Put the measuring cylinder on the mount of the filling volume measuring device, make the measuring cylinder vibrate about 1250 times (about 5 minutes) and read the volume of the sample, and it is accurate to 1 mL (if the surface of the sample is not level after the vibration, it can still be Estimate the volume accurate to 1mL). Continue to vibrate, about 1250 times each time, read the volume of the sample after each time of vibration, until the volume difference of the sample after two consecutive vibrations is less than 2mL, record the final volume of the sample after filling.