5 Surface Modification Methods of Calcium Carbonate
Oct. 20, 2020
Surface modification is an important processing technology necessary to improve the application performance of Calcium Carbonate, improve applicability, expand the market and dosage. At present, there are mainly inorganic surface treatment, organic surface modification, polymer surface modification, mechanochemical modification and Five categories of methods including high-energy surface modification.
1.Calcium carbonate inorganic surface treatment
Calcium carbonate has the disadvantages of poor acid resistance and high pH, which limits its application scope and usage to a large extent. Through the inorganic surface modification treatment of calcium carbonate, a double electrostatic layer can be generated on the surface of calcium carbonate, thereby reducing the mutual repulsion between particles and reducing the accumulation of phenomenon. At the same time, the hydrophilicity of calcium carbonate is increased, so that calcium carbonate can be well wetted in water, thereby increasing the dispersion performance and expanding the scope of application.
Do Su Kim et al. precipitated amorphous silicon on the surface of calcium carbonate through the hydrolysis of silicofluoride ions, thereby improving the acid resistance of calcium carbonate.
2. Surface modification of calcium carbonate organic matter
Organic matter modification mainly refers to the use of chemical or physical methods to wrap the organic matter modifier on the surface of calcium carbonate to change the surface properties of calcium carbonate, so as to increase interface compatibility and reduce mutual agglomeration of powders. It is the best Calcium Carbonate Powder. Mainstream surface modification method.
Commonly used surface modifiers mainly include: fatty acids, phosphate esters, quaternary ammonium salts, silane coupling agents, titanate coupling agents, aluminate coupling agents and composite coupling agents.
Activated Calcium Carbonate
3. Surface modification of calcium carbonate polymer
Polymer surface modification refers to the formation of a core-shell polymer layer on the surface of calcium carbonate particles. Polymer-modified calcium carbonate has two main situations: one is that monomers on the surface of calcium carbonate are polymerized to form polymer segments; the other is to dissolve the polymer in a suitable solvent to form a polymer solution, and Calcium carbonate is added, and the solvent is removed after the polymer gradually adsorbs to the calcium carbonate surface to form a coating. In this way, the polymer can be oriented to adsorb to the surface of calcium carbonate to form an effective adsorption layer, reduce the agglomeration of calcium carbonate particles, improve dispersibility, improve the disadvantages of poor dispersibility of calcium carbonate during use, and achieve the purpose of surface modification
Wu Runde et al. used olefin monomers under the action of the inorganic initiator potassium persulfate to perform in-situ polymerization on the surface of nanometer calcium carbonate to improve the performance of nanometer calcium carbonate.
4. Mechanical and chemical modification of calcium carbonate
Mechanochemical modification is mainly to use strong mechanical force to activate the surface of calcium carbonate particles. The crystal structure of the calcium carbonate surface changes, which makes the crystal lattice move to a certain extent, thereby reacting with other substances. Be enhanced.
By adopting the method of styrene monomer polymerization and grafting, Wu Wei et al. used a mechanochemical method to promote the polymerization of styrene monomer on the surface of calcium carbonate, reducing the amount of initiators, and improving high impact polystyrene (HIPS ) The mechanical properties increase the compatibility between the filler and the matrix.
This method is mainly aimed at the effect of calcium carbonate with larger particles, but for Activated Calcium Carbonate, due to its small particle size, mechanical force does not improve it very well, but it can activate some active sites on the surface. And groups can enhance the interaction with organic surface modifiers, so a combination of mechanochemistry and other modification methods can be used to modify nano-calcium carbonate.
5. High-energy surface modification of calcium carbonate
High-energy surface modification mainly uses high-energy rays, plasma and other methods to modify the surface of inorganic powders. This method mainly relies on high-energy rays and plasma sources to bombard and touch the calcium carbonate surface, so that some reactive sites are generated on the calcium carbonate surface, and then unsaturated monomers are added. The body can react with active sites on the surface to form a coated organic film on the surface of the inorganic particles.
However, the cost of this method is high, the effect after modification is not very stable, and the application is limited to a certain extent.
Muscovite and Phlogopite have good electrical insulation, non-conductivity, acid resistance, alkali resistance and voltage resistance, so they are widely used to make insulating materials in the electronics and electrical industries.