Advanced precipitation technology controlling pH at 9.5 and temperature at 60 °C produces high-dispersibility silica (HDS) like Censil 665, which significantly improves filler–rubber interaction. This optimized manufacturing process reduces mixing energy by 22% and improves wet grip by 15% compared to standard precipitation grades.
The client, a mid-sized commercial tire manufacturer, experienced severe silica agglomeration during the non-productive mixing stage. Their previous filler, a standard precipitated silica with a BET surface area of 160 m²/g, failed to disperse uniformly within the SSBR matrix. This poor dispersion increased the compound's Mooney viscosity by 18%, leading to unacceptable processing delays.
The incumbent supplier's product, comparable to SIPERNAT 500S, utilized a conventional single-step precipitation process that resulted in a broad particle size distribution. This conventional method yielded an oil absorption (DBP) value of 240 g/100g, indicating excessive internal porosity that trapped silane coupling agents. Consequently, the silane coupling efficiency dropped below 65%, leaving unreacted silica surfaces to form hard agglomerates.
The controlled multi-step precipitation technology maintains the reaction pH strictly between 9.0 and 9.5 during the primary nucleation phase. This precise pH control, combined with a curing temperature of 60 °C, creates a highly uniform pore structure with an average pore volume of 1.8 cm³/g. The resulting product, Censil 665, features a narrower particle size distribution with an average primary particle size of 16 nm.
The engineering team selected Censil 665, a high-dispersibility precipitated silica specifically engineered for green tire treads. Censil 665 delivers a BET surface area of 165 m²/g and a CTAB surface area of 155 m²/g, ensuring optimal active sites for silane grafting. Additionally, its optimized morphology provides a bulk density of 320 g/L, which improves pneumatic conveying efficiency by 12% during automated batching.
| Parameter | Previous standard grade | Censil 665 |
|---|---|---|
| BET surface area | 160 m²/g | 165 m²/g |
| CTAB surface area | — | 155 m²/g |
| DBP oil absorption | 240 g/100g | 220 g/100g |
| Average pore volume | — | 1.8 cm³/g |
| Primary particle size | Broad distribution | 16 nm |
| Bulk density | — | 320 g/L |
| Silane coupling efficiency | < 65% | 92% at 4.5 min |
The client integrated Censil 665 into their existing Banbury mixer protocol, adjusting the silane coupling agent dosage to 8.0 wt% relative to the silica weight. Because of the optimized pore volume, the silane grafting reaction reached 92% completion within just 4.5 minutes at a peak drop temperature of 155 °C. This rapid reaction kinetics reduced the overall non-productive mixing cycle time by 22% compared to their baseline formulation.
Dynamic Mechanical Analysis (DMA) revealed a 15% reduction in the tan delta at 60 °C, directly correlating to a proportional decrease in rolling resistance. Simultaneously, the tan delta at 0 °C increased by 12%, demonstrating a significant enhancement in wet grip performance. The final cured compound also exhibited a 20% improvement in tensile strength, reaching 24 MPa at 300% modulus.
| Metric | Change vs. baseline | What it means |
|---|---|---|
| Non-productive mixing cycle | −22% | Lower mixing energy and higher line throughput |
| tan δ at 60 °C | −15% | Proportional reduction in rolling resistance |
| tan δ at 0 °C | +12% | Improved wet grip performance |
| Tensile strength at 300% modulus | +20% (24 MPa) | Higher compound durability |
| Pneumatic conveying efficiency | +12% | Faster, cleaner automated batching |
The primary lesson is that controlling precipitation kinetics is just as critical as the final surface area for achieving high dispersibility. By prioritizing a narrow pore size distribution over maximum porosity, manufacturers can maximize silane coupling efficiency up to 95%. This approach proves that advanced precipitation technology directly translates to measurable energy savings and superior end-product performance.
High-dispersibility silica for green tire treads typically features a BET surface area between 150 and 170 m²/g. For example, Censil 665 provides a highly consistent BET of 165 m²/g to balance rolling resistance and wet grip.
Standard precipitated silica often has a DBP oil absorption above 240 g/100g, which increases compound viscosity. In contrast, Censil 665 is optimized to a DBP value of 220 g/100g, ensuring better flowability during extrusion.
Yes, all precipitated silica products, including the CensilMatt and CensilGuard lines, are manufactured under strict ISO 9001:2015 quality management systems. Production facilities maintain REACH compliance for all European market applications.
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