HIFULL® HB-139 (BET=180㎡/g)

HIFULL® HB-139 is hydrophobic fumed silica which is produced by hydrophilic fumed silica with a specific surface area of 200m2/g after chemical post-treatment with PDMS / Polydimethylsiloxane, also known as silicone oil.

Compared to untreated hydrophilic fumed silica, HB-139 loses its surface hydroxyl groups due to chemical reactions or shielding, making it hydrophobic. Its particle size increases, and the nitrogen adsorption-specific surface area decreases from 200m2/g to around 110±30 m2/g. Its pH ranges from 4.0% to 7.0% in a 4% dispersion of isopropanol-water solution (1:1 volume ratio). The pH change of hydrophobic fumed silica is influenced by the treating agent.

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PropertiesUnitTypical ValueTesting Standard
 Specific surface area(BET)m2/g110±30GB/T 20020
pH value in 4% dispersion4.0~7.0GB/T 20020
Loss on drying(2 hours at 105℃)%≤0.7GB/T 20020
Loss on ignition(2 hours at 1000℃, based on material dried for 2 hours at 105℃)%≤10.0GB/T 20020
Silica Content(Based on ignited material)%≥99.8GB/T 20020
Tamped Density(Based on material dried at 105℃ for 2 hours)g/L45~70GB/T 20020
Carbon Content (Based on material dried at 105℃ for 2 hours)%4.0~7.0GB/T 20020

“Structuring” refers to the phenomenon when rubber compound becomes hard during storage, its plasticity decreases, resulting in lose of properties to be reprocessed or used. PDMS-treated hydrophobic fumed silica enhances the reinforcement performance of silicone rubber without structuring even at high filler concentrations. It is particularly suitable for transparent systems, offering product transparency while providing high hydrophobicity. It exhibits exceptional anti-caking and flow-enhancing characteristics in powder coatings.


Uses and Applications

Due to its unique properties, PDMS or silicone oil-treated hydrophobic fumed silica finds wide applications in various fields such as:

  • silicone rubber
  • coatings & inks
  • adhesives and sealants
  • lubricating oil
  • cable gels
  • vinyl ester resins
  • powder materials

Functional Properties

Thickening and Thixotropic Behavior: The addition of PDMS-treated silica significantly increases the viscosity and thixotropic behavior of formulations. This ensures that the product maintains its thickness during storage and application, yet becomes less viscous when subjected to shear forces, allowing for smooth and effortless spreading.

Anti-Sagging Properties: PDMS-treated silica imparts anti-sagging properties to formulations, preventing the settling or sagging of heavier components. This is particularly important in products with suspensions or high-density ingredients, as it maintains the uniform distribution of particles and prevents undesirable separation.

Stability: With PDMS treatment, silica becomes an excellent stabilizing agent, contributing to the overall stability of formulations. It helps prevent phase separation, settling, or stratification of ingredients, ensuring the product retains its intended appearance, texture, and performance over time.

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Frequently Asked Question

A Manufacturer. Hubei Huifu has been researching and manufacturing fumed silica for 20+ years. We are the largest manufacturer of fumed silica with a well-developed and stable manufacturing process in China.
We get registration of REACH and pre-registration of K-REACH & KKDIK. We get certificates of ISO 9001, ISO 14001. We are the leading setting body of ISO18473-1:2015, ISO18473-3:2018 and ISO 23157:2021.

  • Manufacturer: Leading fumed silica manufacturer in China with 20+ years of expertise, 12,000 tons annual capacity 
  • Registration & Certificate: REACH, K-REACH, KKDIK, ISO9001, HALAL, KOSHER
  • Manufacturer Direct Supply: 23 grades of hydrophilic; hydrophobic fumed silica supplied, good quality, competitive price
  • International Standard: Leading setting body of ISO18473-3-2018 Fumed silica for silicone rubber application; Member of the setting body of ISO18473-1-2015 Nanoscale calcium carbonate for sealant application
  • Technology Expertise: 50+ technology patents experienced R&D team from top universities of China Project 211 & Project 985 

Free Sample: All grades of fumed silica sample available, Contact to Us

Pyrohydrolysi & Trichloromethylsilane

Fumed silica is synthesized by the pyrohydrolysis of silicon tetrachloride or trichloromethylsilane in the flame of hydrogen and oxygen. Our main raw material is silicon tetrachloride, and the secondary is trichloromethylsilane.

Hydrophilic Fumed Silica SiO2:

HL-150 / HL-200 / HL-300 / HL-380 / HL-150W / HL-200W

Hydrophobic Fumed Silica SiO2:

DDS Treated — HB-151/ HB-152 ;
PDMS Treated — HB-139 ;
HMDS Treated — HB-132 / HB-135 / HB-612/ HB-615 / HB-620 / HB-630.

Fumed Titanium Dioxide TiO2: NT-50

Fumed Aluminium Oxide Al2O3: Aluna-80 & Aluna-100

Price is based on the actual grade.

When the price of raw material fluctuates, we may adjust the price accordingly, please enquire before placing orders. Our email: hifull@hifull.com. Cell : + 8618571019514

When fumed silica is used as filler or additives, it helps in thickening, reinforcement, transparency, free-flow, thixotropic performance, dielectric properties, anti-settling, heat insulation, and anti-sagging. For example, for powder products, HIFULL fumed silica is used as an anti-caking agent; for liquid products, HIFULL fumed silica is used as an anti-settling agent or suspending agent.

ApplicationsFunctionsRecommended Dosage
Paints & Coatingsrheology & thixotropic control,anti-sagging,anti-settling0.5-2%
UPR, Gel Coatrheology & thixotropic control,,anti-sagging,anti-settling0.5-2%
HTV Silicone Rubberreinforcement15-30%
RTV Silicone Rubberthickening & reinforcing10-20%
Adhesivesrheology & thixotropic control, anti-sagging,anti-settling2-10%
Cable Gelthickening5-10%
Gel Batterythickening0.5-6%
Industrial Powdersanti-caking0.5-1%

Quality Stabilization: we are the earliest fumed silica manufacturers with independent R&D in China, which guarantees our product stabilization.

Largest Manufacturer: Our annual output of fumed silica is about 12,000 tons.

Strong R&D Team: Besides our own R&D institute and application& technology department, we’ve to build a research center with Sichuan University and Wuhan University, both are top-tier universities in China.

Leading Authority: We have already been the influential enterprise in the silicon industry in China. Doctor Wang Yuelin, the actual controller of Hifull, is the leader of the Sino-Germany project ISO18473-3 << Fumed Silica for Silicon Rubber>> and he is granted the Outstanding Contribution Award by the committee.

Mainly T/T, L/C and D/P, actual payment terms please check with sales when placing orders.

We will arrange delivery immediately according to the manufacturing schedule and conditions. Due to shipping schedule or other factors, please check with sales when placing orders.

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