White corundum 220# (White Fused Alumina F220) for Epoxy Floor Coatings
As an anti-wear filler for floor coatings, electrofused white corundum 220#(white fused alumina F220) is preferred. Brown fused alumina is not recommended due to high iron impurities and risk of rust discoloration. 220 mesh corresponds to a particle size of approximately58‑75μm, complying with FEPA F220 particle size standard. It is applied in epoxy topcoats, epoxy mortar, and epoxy colored sand floors to enhance wear resistance, scratch resistance and surface hardness without affecting film leveling and appearance.
Chemical Indexes
| Item | Index | Remarks |
| Al₂O₃ | ≥99.2% (Preferred: ≥99.5%) | Higher purity ensures better wear resistance and chemical resistance |
| Fe₂O₃ | ≤0.08% (Preferred: ≤0.05%) | Excessive iron oxide causes yellow rust spots on floors, strictly controlled for floor coatings |
| SiO₂ | ≤0.10% | Reduces free silicon and prevents coating film brittleness |
| Na₂O | ≤0.35% | Excessive alkali metal oxides interfere with the curing reaction of epoxy resin |
| Magnetic Substances | ≤20ppm | Eliminates ferromagnetic particles to avoid black spots and rust defects |
| Loss on Ignition (LOI) | ≤0.1% | No free carbon or organic matter to prevent film bubbles and pinholes |
Particle Size Index of 220 Mesh (F220)
- Particle size distribution: Strictly conforms to F220 screening standard. Oversized coarse particles are prohibited to avoid raised granular pits on the coating surface.
- Particle size range: 58‑75μm.
- Excessive ultrafine powder is forbidden: Excessive fine powder will significantly increase the oil absorption value, resulting in sharp viscosity rise, increased resin consumption and brittle coating film.
Physical Performance Indexes
| Item | Technical Parameters | Application Significance for Floor Coatings |
| Mohs Hardness | 9.0 | Provides excellent wear and scratch resistance for floor coatings |
| True Density | 3.90‑4.00 g/cm³ | Ensures stable sedimentation performance of fillers |
| Bulk Density | 1.75‑1.95 g/cm³ | Affects the thixotropy and filling ratio of floor coatings |
| Particle Morphology | Multi-angular block shape | Angular structure improves coating wear resistance; flaky powder fragmentation is not allowed |
| Moisture Content | ≤0.15% | Excessive moisture causes epoxy film bubbles and pinholes; dry sand is mandatory |
| pH Value | 7.0‑9.0 | Weak alkaline property avoids interfering with epoxy curing reaction |
| Oil Absorption Value | ≤8 g/100g | Core index for floor coatings. Excessively high oil absorption consumes massive epoxy resin, causing coating thickening and difficult construction |
| Whiteness | ≥85 | Prevents graying and darkening of colored and light-colored floor coatings |
Additional Application Requirements
- Acid and Alkali Resistance: Resistant to dilute acid and dilute alkali, suitable for the chemical service environment of epoxy floors.
- Free chloride ions and soluble salts free: Conductivity ≤200μS/cm to prevent salt efflorescence, whitening and film bubbling.
- Cleanliness: Free of soil, quartz sand impurities and oversized particulate impurities.
- Packaging & Storage: Moisture-proof packaging with inner moisture-proof bag, 25kg per package.
