Research on the Influence of Powder Coating Particle Size on Coating Quality

The particle size distribution of the powder coating directly affects the fluidity, stability, electrification of the powder coating, the appearance of the coated product film and the spraying operation process parameters, and determines the quality of the powder coating product

The influence of the particle diameter of the powder coating on the glossiness of the coating surface, the fluidity of the powder particles, the powdering rate and the recovery rate are analyzed

When the particle size of the powder coating of 45 m, the gloss of the powder coating up to 80%, the flow amount of 140 g of powder coatings 30s, the extraction rate of 65%, 70% recovery rate of the paint line coatingol.

Powder coating is a solid powder coating, which has the advantages of no solvent, 99% recycling rate, easy automatic production, good appearance, corrosion resistance and outdoor durability.

Therefore, powder coatings have become a popular industrial application for decades and have been paid attention to by countries all over the world.

For the performance of powder coatings, particle size is a very important production parameter, which affects coating characteristics, leveling, powdering rate and recovery rate

1 Experimental part

1.

Polyester resin (industrial grade), Zhejiang Tiansong New Materials Co.

1.

High-speed mixer (GHJ-50), twin-screw powder coating extruder (SLJ-35), vertical mill (ACM-07), crawler tablet crusher (JFY-204), sea Yang Shengshida Coating Machinery Co.
, Ltd.
; electric heating blast constant temperature drying oven (101A-2 type), Shanghai Guangdi Instrument Equipment Co.
, Ltd.
; laser particle size analysis tester (JL-1177 type), Chengdu Jingxin powder test Equipment Co.
, Ltd.
; mirror gloss meter (XGP60 type), Tianjin Xintong Guangda Technology Co.
, Ltd.
; electrostatic spraying device (real 1 type), self-made in the laboratory
.

2 Results and discussion

2.
1 The effect of particle size on gloss

The influence of powder coating particle size on gloss is shown in Figure 1
.
It can be seen from the figure that when the particle size of the powder coating decreases, the gloss of the coating increases, and the particle size of the bright product is basically distributed below 45μm;

When the particle size of the powder coating is too large, the appearance performance of the coating will deteriorate, bubbles appear on the surface, and the orange peel phenomenon is more serious
.

The larger the particle size of the powder, the lower the powder loading rate.
The reason is that its gravity is greater than the aerodynamic force and electrostatic force, which causes the powder particles to fall down before reaching the surface of the product, thus reducing the powder loading rate
.
When the particle size of the powder coating is 45μm, the gloss of the powder coating reaches 80%
.

2.
2 The influence of particle size on leveling

The outflow of powder coatings with different particle sizes in 30S is shown in Figure 2
.
It can be seen from the figure that the larger the particle size of the powder coating, the smaller the amount of outflow within 30s, that is, the smaller the particle size of the powder, the better the leveling of the powder
.
When the particle size of the powder coating is 45μm, the outflow of the powder coating in 30s is 140g
.

2.
3 The influence of particle size on the powder loading rate

The relationship between powder coating rate and powder particle size is shown in Figure 3
.
It can be seen from the figure that the particle size of powder coating suitable for electrostatic spraying is preferably between 30 and 80 μm
.

In order to improve the quality of painted products, the particle size and distribution of powder coatings must be controlled
.
When producing powder coatings, the particle size of the powder coating should be avoided as much as possible while reducing the generation of powder with a particle size of less than 10μm as much as possible
.

Therefore, controlling the particle size of powder coatings is one of the keys to affecting the powder loading rate
.
When the particle size of the powder coating is 45μm, the powder loading rate will reach 65%
.

2.
4 The impact of particle size on recovery

Because the particle size of powder coatings is not single, but a combination of a series of different particle sizes, it has a specific particle size distribution
.

For powder coatings, the narrower the differential distribution of particle size, the better, the filter element of the vibrating screen is not easy to be blocked during processing, high recycling efficiency, and high recycling efficiency are one of the advantages of powder coatings
.
The recycled powder coatings can be mixed with new powder coatings in a certain proportion and then reused
.

The relationship between the recovery rate and the particle size of the powder coating is shown in Figure 4
.
It can be seen from the figure that when the particle size of the powder coating is less than 10μm, the recovery rate is below 10%, which is a low value;

As the particle size of powder coatings continues to increase, the recovery rate of powder coatings also increases.
According to the data, the recovery rate of powder coatings with a particle size of 30-80μm is better
.
When the particle size of the powder coating is 45μm, the recovery rate reaches 70%
.

3 Conclusion

The influence of the particle diameter of the powder coating on the glossiness of the coating surface, the fluidity of the powder particles, the powdering rate and the recovery rate were studied
.

The experimental results show that when the particle size of the powder coating is 45μm, the gloss of the powder coating reaches 80%, the flow rate of the powder coating within 30s is 140g, the powdering rate reaches 65%, and the recovery rate reaches 70%.
The overall performance of the powder coating Excellent, meets the requirements of production and use, and has good application prospects
.