The size of organic pigment particles has a great influence on the color performance of coatings.
On the one hand, it affects the covering power and coloring power of the paint, within a certain range of pigment particle size, the covering power of the paint increases; when the pigment particles become small, the specific surface increases, and the coloring power of the paint increases. Pigment particle size also has an effect on the color light of the paint, usually the particle size is large, the particle size distribution is wide, the color light is dark; on the contrary, the color light is bright.
On the other hand, pigment particle size also affects the UV resistance of paint. When the particle becomes small, the specific surface area increases, the absorbed light energy increases, the degree of destruction also increases, so the paint fades faster. Pigment particle size is small, the gravity is small, the paint is not easy to stratify and precipitate; but the pigment with small particle size has large specific surface area, the surface energy increases so that the chance of flocculation and roughness of the paint increases, which is not conducive to grinding and dispersion.
Most organic pigments exist in crystal state, and the phenomenon of "homogeneous heterocrystal" is very common. Copper phthalocyanine crystal, common Q-type red blue (such as pigment blue 15) poor stability, after specific solvent treatment is turned into a stable P-type green blue (such as 15:3); pigment violet 19 (quinolone structure) has α, β and γ 3 kinds of crystal, α-type has no value, β-type for the purple-red, and γ-type for the blue red.
In the design of coating formulations, pay attention to the rational use of additives and solvents to prevent different crystal types from transforming under certain conditions, which will cause the coating to undergo chromatic drift and make it difficult to find the right color acco
