Overview
HJSIL R620 is a hydrophobic fumed silica treated with HMDS (hexamethyldisilazane), based on hydrophilic fumed silica with a BET surface area of 200–220 m²/g. Supplied as a high-purity white colloidal powder with a post-treatment BET surface area of 190 ± 10 m²/g. It delivers good reinforcement and transparency for HTV and liquid silicone rubber, high hydrophobicity and stable thixotropy for coatings and inks, good dispersibility for anti-foam formulations, and improved free flow and homogeneity of carbon powder for printers.
Technical Specifications
| Property | Unit | Value | Standard |
|---|---|---|---|
| Specific surface area (BET) | m²/g | 190 ± 10 | GB/T 10722 |
| pH value (4% dispersion) | — | 5.5–8.0 | GB/T 1717 |
| Loss on drying (105°C, 2 hrs) | Wt% | ≤0.7 | GB/T 5211.3 |
| Loss on ignition (1000°C, 2 hrs) | Wt% | ≤4.0 | GB/T 20020 |
| Silica content | Wt% | ≥99.8 | GB/T 20020 |
| Tamped density | g/L | 40–60 | GB/T 5211.4 |
| Carbon content | Wt% | 1.5–2.1 | GB/T 20020 |
| Surface treatment | — | HMDS (hexamethyldisilazane) | — |
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Applications
- Elastomer, HTV, and liquid silicone rubber
- Coatings and inks
- Anti-foamer
- Carbon powder for printer
Key Properties
- Good reinforcement and transparency for HTV and liquid silicone rubber
- High hydrophobicity and stable thixotropy for coatings and inks (anti-caking, anti-sagging)
- High surface area with good dispersibility for anti-foam formulations
- Improve free flow and homogeneity of carbon powder
Packaging & Storage
Supplied in 10 kg kraft paper bags. Store in closed containers under dry conditions and protect from volatile substances.
Related Products
- HJSIL® Fumed Silica
- HJSIL R110 — PDMS-treated hydrophobic fumed silica, 100 m²/g BET
- HJSIL R272 — DDS-treated hydrophobic fumed silica, 110 m²/g BET
- HJSIL R274 — DDS-treated hydrophobic fumed silica, 170 m²/g BET
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