Effect of surface treatment of inorganic pigments
Surface treatment of inorganic pigments
After the surface treatment of inorganic pigments, application performance of pigments can be further improved ,and the results fully reflect its optical properties,that is one of the main measures to improve the quality grade of pigments .
The role of a surface treatment
The effect of surface treatment can be summarized into the following three aspects:
- to improve the properties of the pigment itself, such as the coloring power and hiding power;
- improve performance, and enhance the dispersibility and dispersion stability of the pigment in a solvent and the resin;
- improve the pigment final goods durability, chemical stability and processability.
Surface treatment of the pigment can be done by an inorganic coat and add organic surface-active agents to achieve its object, for example:
Chrome yellow swell easily in the manufacturing process, to thicken when the toner prone to “silk”, by adding zinc soaps, aluminum phosphate, aluminum hydroxide to reduce the coarse acicular crystals, lower swell phenomenon; lead chrome yellow pigments can be used antimony compound or a rare earth or silica surface treated to improve its light resistance, heat resistance and chemical stability; cadmium yellow surface area can be increased through SiO2, Al2O3 surface treatment, to enhance weather resistance, can also be added sodium stearate, alkyl sulfonates, etc. to the surface from hydrophilic to lipophilic and more easily dispersed in the resin;
Cadmium red by Al2O3, SiO2 coated surface treatment may also improve its dispersibility and weather resistance ;
Iron oxide pigment may be surface treated with stearic acid agent to improve its dispersibility in an organic medium, the surface treatment can also be Al2O3 , oleophilic surface to enhance performance ;
Transparent yellow iron oxide , it can improve the dispersibility and transparency by adding sodium dodecyl naphthalene surface treatment ;
Iron blue pigments poor alkali resistance , alkali resistance can be enhanced by its fatty amine surface treatment ;
Ultramarine poor acid resistance , acid can improve its performance by SiO2 surface treatment ;
Lithopone Lithopone in zinc sulfide can be reduced by photochemical activity of rare earth elements in surface treatment .