Fumed Silica "REOLOSIL"

REOLOSIL is a very fine amorphous silicon dioxide produced by Tokuyama with a diameter between 5 and 50 nanometers. Its surface structure and agglomerated structure after dispersions contributes to viscosity and thixotropy in liquid resins. It is widely used as a reinforcing filler for rubber and elastomeric materials, as well as for fluidization and prevention of caking in powder materials. It can be used in a wide range of other applications thanks to its high level of purity and ultrafine particles.

Product overview

Generic names Fumed Silica
Product name REOLOSIL
Chemical formula SiO2
Packing /
shipping method
Flexible containers, paper bags
General applications
  • Unsaturated polyester resins
  • Silicone resins and urethane resins
  • Semiconductor field (CMP slurry)
  • Various types of paint
  • Various types of inks
  • Various types of adhesives
  • Inkjet paper
  • Shoe soles (clear rubber)
  • Water-absorbing resin
  • Toner

Special characteristics

  • High purity: REOLOSIL is manufactured using highly purified raw materials under strict process controls. Since REOLOSIL is high purified silica with a trace of impurities, it can be used in semiconductor materials requiring a high level of purity, including CMP slurry.
  • High dispersion: REOLOSIL microparticles are manufactured through a vapor release reaction and form loose agglomerates. By dispersing moderately, it is possible to disperse particles smaller than the wavelength range of visible light.
  • High specific surface area: The specific surface area for fumed silica is generally about 50-500m2/g, with primary particles 5-50nm in diameter. Because it is produced at a high temperature in a gas phase, it is an amorphous silica with no internal surface area.
  • Surface chemistry: REOLOSIL is available in various hydrophilic grades and hydrophobic grades produced from hydrophilic silica through hydrophobic surface treatment. According to the application objectives of the powder, REOLOSIL can be dispersed in various dispersion media, including liquid and powder.

Key properties and effects

  • Thickening and thixotropy:REOLOSIL provides thickening and thixotropic effects in liquid systems such as polyesters, epoxies, and urethane resins due to interaction between aggregates and the development of three-dimensional networks between REOLOSIL particles
  • Reinforcement:Adding REOLOSIL as a filler material improves various mechanical properties of elastomers, including modulus, elongation at break, tensile strength and tear resistance. REOLOSIL’s large specific surface area also makes it possible to achieve excellent transparency in elastomers
  • Anti-settling effects:REOLOSIL improves the suspension behavior in liquid systems, such as pigmented coatings or resins containing fillers
  • Anti-caking, effects for improved flow characteristics:Due to a property that makes it behave like ball bearings, REOLOSIL resists lumping and clogging. It can be used to improve the storage stability of powders that are especially prone to caking. REOLOSIL can also be used to improve flow characteristics and prevent flow problems
  • Anti-blocking effects:REOLOSIL is added to film resins to reduce “sticking”.It reduces close contact between film layers
  • Adsorbent:Gaseous, liquid or solid materials can be precipitated or adsorbed on the surface of REOLOSIL. This serves as an ideal carrier or substrate for active ingredients due to its high specific surface area and inertness in the presence of all chemicals except strong alkalis and hydrofluoric acid
  • Insulation:With its very low solid state conductivity and vast spacing between particles, REOLOSIL provides excellent electrical and thermal insulation properties
  • Electrical charge:Hydrophobic REOLOSIL is used as a toner additive to stabilize electrical charge characteristics. TOKUYAMA can provide Hydrophobic REOLOSIL grades manufactured to custom specifications
  • Polishing:In the semiconductor manufacturing process, the planarization of silicon wafers is achieved via CMP (Chemical Mechanical Polishing) processes such as ILD, STI and metal CMP.REOLOSIL is used in certain CMP slurries as a polishing agent, due to high purity, sub-micron particle size and its distribution characteristics

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