The influence of average particle size of matting powder on coating
1. Relationship between average particle size and transparency: transparency becomes worse with the increase of average particle size.Transparency refers to the good particle size of the powder with the property that the object penetrates through visible light and scatters less. Generally, it should be 1/2 of the wave length of the light in the air, i.e. 0.2-0.4m. Below this value, the powder will lose its ability to scatter light.The powder is usually a mixture of different particle sizes, ranging from 0.01 to 50m. In the system, the smaller the particle size of extinction powder is, the less scattered visible light is, and a large number of incident light rays pass through the extinction powder due to diffraction, so the better the transparency of the system is.However, if the average particle size is too small, fewer particles will play the role of extinction, which cannot play the due role of extinction.When the average particle size is in harmony with the thickness of the coating, the larger the average particle size is, the better the extinction effect of extinction powder is.Therefore, the factors of extinction, transparency and film thickness should be taken into account when selecting matting powder, and the matting powder that meets the requirements should be selected through comparative tests.
2. Relationship between average particle size and anti-sinking ability: in the same system, with the same time of placement, the system with large average particle size has a fast settling rate and is easy to form hard precipitation.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. Relation between average particle size and extinction property: the larger the average particle size is, the better the extinction effect of coating is;The smaller the average particle size, the better the transparency of coating.In the process of selecting matting powder, a series of comparative tests should be carried out to make the matting and transparent properties meet the practical requirements.The smaller the average particle size distribution is, the higher the viscosity of the system will be and the lower the settlement rate will be. Therefore, the factors of extinction and sedimentation should be taken into consideration when selecting extinction powder.
The Effect of Matting Powder porosity on Coatings
Matting 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 roughness needed for extinction.With the same particle size, the higher the porosity, the higher the extinction efficiency.
The Effect of Matting Powder surface treatment on Coating
1. The organic wax treated matting powder has small oil absorption and easy to separate and settle, but soft precipitates, and the matting agent treated by organic matter is lower than the matting efficiency of equivalent untreated matting powder.
2. untreated matting powder, large oil absorption, large thixotropy, not easy to stratify sedimentation, but easy to produce hard precipitation, transparency and matting is better than the equivalent wax processing matting powder.
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