The influence of the average particle size of extinction powder on the coating
1. Relationship between average particle size and transparency: with the increase of average particle size, transparency becomes worse.
Transparency refers to the good particle size of powders with properties that objects penetrate visible light and scatter less. Generally, the wavelength of light in the air is 1/2, that is, 0.2-0.4 m, greater than this value, the total surface area of powders decreases, and the total scattering ability of light decreases.
Below this value, the powder will lose its ability to scatter light.
Powders are usually mixtures of different particle sizes ranging from 0.01 to 50m.
In the system, the smaller the particle size of extinction powder is, the less visible light will be scattered, and a large amount of incident light will pass through the extinction powder due to diffraction. Therefore, the transparency of the system is better.
But the average particle size is too small, play the role of extinction of the particles will be less, can not play the role of extinction.
When the average particle size is in harmony with the film thickness, the larger the average particle size is, the better the extinction effect of the extinction powder will be.
Therefore, the factors of extinction, transparency and film thickness should be considered in the selection of extinction powder.
2. The relationship between average particle size and anti-sinkability: in the same system, the system with a large average particle size was placed for the same time, and the settling rate of powder was fast and hard precipitation was easily formed.
The square of particle size is proportional to the settling rate, so the larger the average particle size is, the faster the settling rate will be.
3, the relationship between average particle size and extinction: the larger the average particle size, the better the coating extinction effect;
The smaller the average particle size, the better the transparency of the coating.
In the process of selecting matting powder, a series of comparative tests should be carried out to make the matting and transparency properties meet the actual application requirements.
The smaller the average particle size distribution is, the higher the viscosity of the system will be, and the sedimentation rate will also be reduced.
Second, extinction powder porosity of the coating
Degussa deluster OK520
Degussa deluster OK520
Dulling agent generally like a small sponge, there are many internal pores.
The particles with higher porosity are lighter and thus have more particles per unit mass because they produce the micro-roughness required for extinction.
With the same particle size, the higher the porosity, the higher the extinction efficiency.
The influence of matting powder surface treatment on coating
1, the organic wax treatment of extinction powder, oil absorption is small, easy stratification sedimentation, but soft precipitation, and the organic treatment of the extinction of extinction agent than the equivalent of no treatment of extinction powder extinction efficiency is lower.
2, the untreated extinction powder, oil absorption, thixotropy, not easy to stratify settlement, but easy to produce hard precipitation, transparency and extinction is better than the equivalent wax treatment extinction powder.