The main mineral in bentonite is montmorillonite, and the basic structural form of montmorillonite is a TOT type, that is, two layers of silica tetrahedron sandwiched with one layer of aluminum oxide octahedron to form a layered structure. This special layered structure endows bentonite with special properties, such as water absorption, swelling, thixotropy, and rheology. These properties make it have a good application in the paint industry.
Five Advantages of Bentonite in Paint Application
1. Thickening effect: Bentonite forms flocculent substances in water, which has a thickening effect. Its molecular groups can combine with the organic base materials in the coating, enhancing the water resistance of the coating, and improving the strength and adhesion of the coating.
2. Suspension and dispersibility: Bentonite has good suspension and dispersibility in aqueous media, making the coating difficult to precipitate, difficult to layer, and uniform in color, thereby improving the stability of the coating suspension. Moreover, it has good brushing performance, and can form a uniform, flat, and smooth coating. Based on this, some heavy calcium carbonate can be added to the coating to reduce costs.
3. Adhesion and hiding power: Bentonite has a certain adhesion and hiding power, and its price is low. Adding it to a series of polyvinyl alcohol glues can greatly reduce the amount of polyvinyl alcohol and its fillers (such as light calcium carbonate), resulting in lower product costs.
4. Hydrophilicity, plasticity, expansibility, and adhesiveness: Bentonite has excellent hydrophilicity, plasticity, expansibility, and adhesiveness. It can be combined with an appropriate amount of water to form a colloid, which can release charged ions in water. This ionic repulsion makes it act as a dispersant in coatings. In waterproof coatings, bentonite particles in high-speed motion collide and cut with hot asphalt, crushing and gelatinizing the asphalt. The polar substances in the gelled asphalt particles adsorb the bentonite particles, forming a colloidal hydration film on the surface of the asphalt particles, reducing the interfacial tension between the asphalt and water, preventing the asphalt particles from agglomerating again, thereby forming a stable dispersion phase, which acts as an emulsifier.
5. Cold resistance: Bentonite has cold resistance, and the prepared coating can still be used at lower temperatures in winter.
Post time: Mar-24-2023