The application of silica in coatings mainly involves improving adhesion, weather resistance, anti settling, and enhancing thixotropy, and is suitable for building coatings, water-based coatings, acrylic resin paints, etc.
1、 Compatibility between silica types and paint systems
1. Gas phase silica
① Application areas: UV curable paint (such as UV wood paint, UV plastic coating), industrial thick paste coating, powder coating.
② Performance advantages: Strong thixotropy, significant anti sagging and anti settling effects (such as adding 1.5% HL-200 can increase the viscosity of UV plastic coatings by 675%).
The wear resistance is outstanding, and the addition of 2% HL-200 increases the wear resistance of UV wood paint by 54.3%.
③ Cost impact: The unit price is high (300-800 yuan/kg), but the addition amount is low (0.5% -3%), and the overall cost is controllable.
2. Precipitation method silica
① Application areas: Architectural coatings, mid to low end industrial coatings.
② Performance advantages: Low cost (10-30 yuan/kg), but requires high dosage (3% -10%), and the extinction effect is better than that of gas-phase method.
③ Limitations: Wide particle size distribution, low rheological control accuracy.
3. Aerogel silica
① Special applications: fireproof coatings, high-temperature equipment protective coatings.
② Cost issue: The preparation process is complex, with a cost of up to 10000 yuan/kg, and is only used in high value-added fields.
2、 Improvement of coating performance
1. Rheology and construction performance optimization
Gas phase silica forms a three-dimensional network structure through surface hydroxyl groups, endowing the coating with thixotropy: it reduces viscosity under shear force for easy application, recovers thickening when standing, and prevents sagging and thick edges.
The precipitation method of silica can enhance the stability of coatings, prevent pigment settling, and extend storage life.
2. Anti caking and improved dispersibility
Ultra fine silica, as an external additive, adsorbs onto the surface of powder coatings to form a "ball rolling" effect, improving fluidity and anti caking ability.
The high surface energy of fumed silica can shorten dispersion time and improve pigment uniformity.
3. Functional enhancement
① Extinction effect: Silicon dioxide particles reduce coating gloss through diffuse reflection, achieving a matte to semi matte effect.
② Mechanical performance: Improve coating hardness, wear resistance, and weather resistance, and extend service life.
③ Optical performance: UV scattering enhances anti-aging ability while maintaining transparency.
4. Special application scenarios
① Ship paint and other thick paste coatings rely on the thixotropy of fumed silica to ensure construction thickness.
② Used in floor paint to improve leveling and scratch resistance.
③ Different types of silica (gas-phase method/precipitation method) need to be selected according to the requirements of the coating system. For example, gas-phase method is more suitable for high-precision rheological control, while precipitation method has more advantages in balancing extinction and cost.
3、 Suggestions for balancing cost and performance
1. High end coatings (such as automotive paint, UV paint): Preferred is fumed silica, which has a high unit price but significantly improves performance (such as doubling wear resistance). ‌
2. Mid to low end coatings (such as architectural coatings): The precipitation method has a higher cost-effectiveness and can improve compatibility through surface modification (such as KH-570).
3. Special functional requirements (fire protection/heat insulation): aerogel silica cannot be replaced, but the cost-effectiveness needs to be comprehensively evaluated.
Silicon dioxide in the coating industry indirectly reduces overall costs through performance improvement, but it requires a balance between raw material prices and process inputs. The high-end field tends to use gas-phase method, while the mid to low end market chooses the precipitation method for better cost-effectiveness.