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Fumed silica delivers reliable reinforcement, but it is also one of the most expensive components in a rubber or sealant formulation.
For manufacturers facing cost pressure, the practical question is not whether to replace fumed silica completely, but how far it can be partially replaced without sacrificing performance.
IOTA FINE SIL 7325 is a superfine precipitated silica designed for partial or full replacement of fumed silica in suitable formulations.
Precipitated silica offers reinforcement at a significantly lower cost than fumed silica.
For general rubber goods, cost-sensitive compounds and carrier applications, a well-selected precipitated grade can reduce raw material cost while maintaining the required physical properties.
The key is understanding where the substitution works — and where it does not.
IOTA FINE SIL 7325 is a superfine precipitated silicon dioxide produced by a special processing technology, with good reinforcement and dispersion.
Its published product information includes:
|
Property |
Typical specification |
|
SiO2 (dried) |
≥ 90% |
|
Moisture |
4–8% |
|
Sulphate |
≤ 1.5% |
|
pH value |
6.5–7.5 |
|
Iron content |
≤ 1000 mg/kg |
|
BET specific surface area |
160–180 m²/g |
|
Particle size |
35 μm |
|
Packing |
20 kg bag |
These are typical product values, not guaranteed specifications for every batch or for the properties of the final compound.
Rubber reinforcement
For tyres, footwear and general rubber products, FINE SIL 7325 can be evaluated as a reinforcing filler to improve flex resistance, anti-cracking performance and physical properties, with high wear resistance and strength.
Carrier and filler applications
With low-impurity treatment, its high specific surface area makes it suitable as a carrier in feed additives, pesticides, agriculture and laundry powder, improving the fluidity of powders.
A stepwise substitution is recommended.
Start with 10–30% of the fumed silica replaced by FINE SIL 7325, keeping total filler volume constant.
Compare:
If properties remain acceptable, increase the substitution ratio step by step until the cost-performance balance is reached.
Full replacement is possible in some general-purpose compounds, but should always be confirmed by testing.
Check the moisture.
Precipitated grades carry higher moisture (4–8%) than fumed grades. Review drying procedures and storage conditions of the compound.
Check the pH.
The pH difference (6.5–7.5) may affect cure behavior in some systems. Verify scorch safety and cure characteristics.
Check the application requirements.
For transparent, high-strength or high-specification compounds, fumed silica may still be required as the primary reinforcement.
1. Can FINE SIL 7325 fully replace fumed silica?
In some general rubber compounds, yes. In high-specification systems, partial replacement is the realistic starting point.
2. Will the compound color change?
Precipitated grades are suitable where high transparency is not critical. Evaluate the finished appearance in the trial.
3. Does the higher moisture cause problems?
It can affect some moisture-sensitive systems. Check drying, packaging and storage stability during the trial.
4. What information should buyers provide?
Provide the compound type, current silica grade and loading, target properties and cost target.
IOTA FINE SIL 7325 Precipitated Silica
Product page: https://www.iotasilica.com/product-precipitated-silica-iota-fine-sil7325.html
Final suitability should be confirmed through controlled testing in the intended formulation.
