Five advantages of bentonite in coating applications
01
Has a thickening effect: bentonite forms a flocculent substance in water, which has a thickening effect, and its molecular groups can be combined with the organic base material in the coating, which can enhance the water resistance of the coating and improve the strength and adhesion of the coating.
02
Suspension and dispersion: bentonite has good suspension and dispersion in the water medium, so that the paint is not easy to precipitate, not easy to layer, uniform color, thereby improving the stability of the paint suspension, and good brushing performance, can form a uniform thickness, smooth and smooth coating. Based on this, some heavy calcium carbonate can be added to the paint, thus reducing the cost.
03
Adhesion and hiding power: Bentonite has a certain adhesion and hiding power, and the price is low, add it to the polyvinyl alcohol series glue, can make the amount of polyvinyl alcohol and its filler (such as light calcium carbonate) greatly reduced, so that the cost of the product is reduced.
04
Hydrophilicity, plasticity, expansion, bonding: bentonite has excellent hydrophilicity, plasticity, expansion, bonding, and can be combined with the right amount of water into a colloid, in the water can release charged ions, the electrical repulsion between ions, so that it plays the role of dispersant in the paint. In waterproof coating, bentonite colloidal particles in high speed movement collide with hot asphalt and cut, breaking and gumming 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 asphalt and water, preventing the asphalt particles from re-condensing, thus forming a stable dispersed phase and acting as an emulsifier.
05
With cold resistance: Bentonite has cold resistance, and the prepared coating can still be used at lower temperatures in winter.
Note in paint application
01
For organobentonite, due to the different cationic organics introduced during modification, the adaptability of organobentonite to solvents is also different, resulting in some organobentonite will destroy or interfere with hydrogen bonds in highly polar solvent environment, resulting in the anti-settling effect of the system is not ideal.
02
Bentonite is a powdery rheological agent, which has certain difficulties in addition and may be difficult to disperse, especially for small experiments in the laboratory, it is difficult to grasp the temperature and dispersion, and the measured data has a large error.
03
Bentonite has a great influence on the gloss of the coating film. When the amount of bentonite reaches 20% of the total formula, the coating loses light seriously, and the surface is dry, easy to crack and brittle.
04
The whiteness of bentonite is low, and it has a bad effect on the leveling of paint.
Sum up
Bentonite in the paint is mainly used as an additive, such as thickener, anti-settling agent, dispersant, etc., the addition amount is generally between 0.2% and 2%, the impact on other properties of the paint is not very large, mainly to prevent the settlement of the pigment filler in the paint.
Post time: 2024-04-30 10:00:07
