Precipitated silica is the leading mineral reinforcement for rubber and a multi-functional additive across food, feed, and personal care. This guide covers application categories, grade requirements, and selection criteria.
What Is Precipitated Silica
Precipitated silica (SiO₂·nH₂O) is an amorphous white powder made by controlled acidification of sodium silicate. Unlike fumed silica (flame hydrolysis), it is produced via aqueous precipitation, allowing manufacturers to tune BET, particle size, and oil absorption across a wide spectrum.
| Metric | Value |
|---|---|
| Rolling resistance reduction vs. carbon black (green tire tread) | 20% |
| Max BET surface area for specialty HD rubber grades | 280 m²/g |
| Upper limit for oral-care abrasive grades | 150 RDA |
| EU food additive number for anti-caking use | E551 |
Rubber & Tire Reinforcement
The cornerstone of "green tire" technology — silica at 60–90 phr with a silane coupling agent (TESPT or TESPD) cuts rolling resistance by 15–20% versus carbon black, reducing fuel consumption by 4–8%.
Passenger & EV Tire Treads
60–90 phr HD silica + silane system; lowers rolling resistance and improves wet grip simultaneously.
Footwear Soles
Improves tear strength, abrasion resistance, and slip resistance in transparent or light-colored compounds.
Industrial Hoses & Belts
High-surface-area grades reinforce EPDM and SBR for conveyor belts and hydraulic hoses.
Silicone Rubber (HTV/RTV)
Specialty grades provide reinforcement in silicone compounds for electrical insulation and food-contact parts.
Animal Feed & Nutrition Additives
Feed-grade precipitated silica at 0.5–1.5% functions as a free-flow aid and liquid carrier — absorbing liquid vitamins and amino acid solutions into free-flowing powders. Approved under EU (EC) No 183/2005 and FDA GRAS.
Oral Care: Toothpaste & Dental Products
| Grade Type | RDA Range | Primary Function | Typical Load |
|---|---|---|---|
| Cleaning silica | 80–150 | Plaque & stain removal | 15–25% |
| Thickening silica | <30 | Rheology & gel structure | 3–8% |
| Whitening silica | 100–200 | Enhanced stain removal | 10–20% |
| Transparent silica | 40–80 | Optical clarity in gel paste | 15–22% |
Food Anti-Caking & Industrial Carrier
As food additive E551, precipitated silica keeps powdered sugar, spice blends, and instant mixes free-flowing by absorbing surface moisture. In agrochemicals, it absorbs liquid actives to produce stable, free-flowing powders.
Grade Selection Guide
| Application | BET Surface Area | Oil Absorption | Key Parameter |
|---|---|---|---|
| Tire tread (HD) | 150–200 m²/g | 200–260 mL/100g | CTAB ≥150 m²/g |
| General rubber | 100–160 m²/g | 180–240 mL/100g | DBP absorption |
| Toothpaste abrasive | 60–120 m²/g | 150–220 mL/100g | RDA 80–150 |
| Toothpaste thickener | 200–280 m²/g | 280–340 mL/100g | pH compatibility |
| Feed / food carrier | 80–150 m²/g | 200–300 mL/100g | SiO₂ ≥98%, E551 |
| Anti-caking agent | 40–80 m²/g | 150–200 mL/100g | Moisture ≤6% |
Browse our precipitated silica product range or contact Semitech with your target BET, oil absorption, and regulatory requirements.
Related Products
Precipitated Silica
Serve as the premium-grade precipitated hydrated silica specifically engineered to serve as the primary friction agent in modern toothpaste formulations.
Fumed Silica
Select the optimal hydrophilic or hydrophobic grade based on your resin system’s polarity and viscosity requirements.
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Frequently Asked Questions
+What is the difference between precipitated silica and fumed silica?
Precipitated silica is wet-chemical, porous, ideal for rubber reinforcement and absorption. Fumed silica is flame-hydrolysis, lower-density, suited for rheology control in coatings and adhesives.
+How does precipitated silica reduce tire rolling resistance?
Silane coupling agent bonds silanol groups to the rubber polymer, creating a tight silica-rubber network that lowers hysteresis energy loss while maintaining wet grip.
+Is precipitated silica approved for use in toothpaste?
Yes — meets FDA 21 CFR 182.90 and EU (EC) No 231/2012. Widely used as a gentle abrasive (RDA 50–150) and thickener.
+What grades are recommended for rubber compounding?
Standard grades: BET 160–200 m²/g, CTAB 140–180 m²/g. HD grades feature optimized aggregate morphology for improved dispersion. See our precipitated silica range.
+Can precipitated silica prevent powder caking in food products?
Yes. Coarse-grade (BET 40–80 m²/g) approved as E551 is used at 0.5–2% in powdered sugar, spice blends, and instant mixes.