The application of silica in coatings mainly involves improving adhesion, weather resistance, anti-settling properties, and enhancing thixotropy. It is suitable for architectural coatings, water-based coatings, and acrylic resin paints.
I. Compatibility of Silica Types with Coating Systems
1. Fumed Silica
Application Areas: UV-curable coatings (e.g., UV wood coatings, UV plastic coatings), industrial thick-film coatings, and powder coatings.
Performance Advantages: Strong thixotropy, excellent anti-sagging and anti-settling effects.
Cost Impact: Although unit price is high, the required dosage is low (0.5%–3%), making overall cost controllable.
2. Precipitated Silica
Application Areas: Architectural coatings, mid- to low-end industrial coatings.
Performance Advantages: Lower cost, though higher dosage is required (3%–10%); better matting effect compared to fumed silica.
Limitations: Broad particle size distribution, lower precision in rheology control.
3. Silica Aerogel
Special Applications: Fireproof coatings, protective coatings for high-temperature equipment.
Cost Issue: Complex preparation process; cost reaches tens of thousands of RMB/kg, thus used only in high value-added fields.
II. Improvements to Coating Performance
1. Rheology and Application Performance Optimization
Fumed silica forms a three-dimensional network structure through surface hydroxyl groups, imparting thixotropy: under shear force, viscosity decreases to facilitate application; when static, viscosity recovers to prevent sagging and edge build-up. Precipitated silica enhances coating stability, prevents pigment settling, and extends storage life.
2. Anti-Caking and Improved Dispersibility
Ultrafine silica, as an external additive, adsorbs on the surface of powder coatings to create a “ball-bearing effect,” improving flowability and resistance to caking. The high surface energy of fumed silica shortens dispersion time and improves pigment uniformity.
3. Functional Enhancement
Matting Effect: Silica microparticles reduce gloss through diffuse reflection, achieving matte to semi-matte finishes.
Mechanical Properties: Improves coating hardness, abrasion resistance, and weather resistance, extending service life.
Optical Properties: Enhances UV scattering for anti-aging capability while maintaining transparency.
4. Special Application Scenarios
Thick-film coatings (e.g., marine paints): Depend on fumed silica thixotropy to ensure film thickness.
Floor coatings: Improve leveling and scratch resistance.
Type Selection: Different silica types (fumed/precipitated) should be chosen based on coating requirements—for example, fumed silica for precise rheology control, while precipitated silica offers better cost-performance balance in matting.
III. Recommendations for Balancing Cost and Performance
High-end coatings (e.g., automotive coatings, UV coatings): Fumed silica is preferred, despite its high unit price, as it significantly enhances performance (e.g., doubling abrasion resistance).
Mid- to low-end coatings (e.g., architectural coatings): Precipitated silica offers better cost-performance ratio, and compatibility can be improved via surface modification.
Special functional requirements (fireproof/thermal insulation): Silica aerogel is irreplaceable but requires a comprehensive evaluation of cost-effectiveness.
Conclusion: In the coatings industry, silica reduces overall cost indirectly by enhancing performance. However, raw material price and process investment must be balanced. High-end applications tend to use fumed silica, while mid- to low-end markets favor precipitated silica for better cost-effectiveness.
Post time: Sep-24-2025