Key Questions to Ask When Ordering hydrophobic pyrogenic silica

30, Dec. 2024

 

Hydrophilic and hydrophobic pyrogenic silicas

We present the following silicas for the coatings sector

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KemituraSil® 200 is a medium surface fumed silica that imparts significant increase in viscosity in

liquid systems, free flow of powders, and reinforcement of silicone and organic rubbers.

is characterized by:

  • High purity
  • Aggregate structure
  • Submicron particle size
  • Low bulk density
  • Hydrophilic surface

Application Information:

  • Rheology Control for Coatings, Adhesive, and other Liquid Systems:

KemituraSil® 200 is widely used to provide thickening, thixotropic (shear thinning), and anti-settling behavior in liquid systems. KemituraSil® 200 is most efficient in non-polar to medium polarity systems. For more polar systems, treated fumed silicas are more effective. KemituraSil® 200 offers the best balance of thickening efficiency and dispersibility.

  • Free-flow of Powder Systems:

When blended into sticky and poorly flowing powder systems, KemituraSil® 200 reduces the angle of repose and improves powder flow. During storage of powder systems, KemituraSil® 200 reduces caking and blocking.

  • Reinforcement of Silicone and Organic Rubber:

KemituraSil® 200 can be used for reinforcement of silicone rubber and can be used to reinforce organic rubbers. It imparts a good increase in hardness, tensile, and elongation.

KemituraSil® 380: is a very high surface fumed silica that can increase the viscosity of liquid systems and provide significant reinforcement of silicone and organic rubbers.

is characterized by:

  • High purity
  • Aggregate structure
  • Submicron particle size
  • Low bulk density
  • Hydrophilic surface

Application Information:

Rheology Control for Coatings, Adhesive, and other Liquid Systems:

KemituraSil® 380 can be used to provide thickening, thixotropic (shear-thinning), and anti-settling behavior in liquid systems. Very high shear dispersion equipment is required to realize the full benefits of 380. 

For clear coatings and other systems, very well dispersed 380 provides the greatest transparency.

Untreated fumed silicas are most efficient in non-polar to medium polar systems. For polar systems treated fumed silicas may be more efficient.

Reinforcement of Silicone and Organic Rubber:

KemituraSil® 380 can be used for reinforcement of silicone rubber and can be used to reinforce organic rubbers. It imparts a good increase in hardness, tensile, and elongation. For clear silicone rubber applications, very well dispersed 380 provides the greatest transparency

KemituraSil® AM-1-120 is a low surface area fumed silica that has been surface treated. The treatment replaces some of the hydroxyls on the surface of the silica resulting in increased hydrophobicity and very different performance than untreated silica. 

 is characterized by: 

  • High purity 
  • Aggregate structure 
  • Submicron particle size 
  • Low bulk density 
  • Hydrophobic surface chemistry 

Application Information: 

KemituraSil® AM-1-120 is used primarily for rheology control in non-polar to medium polarity inks, coatings and adhesives, and free-flow additive for powder systems.

  • Ink, Coating, and Adhesive Systems:

Like an untreated fumed silica the mechanism for thickening is hydrogen bonding between hydroxyl groups so AM-1-120 can be an effective thickener of non-polar to medium polarity systems. Although the thickening potential is lower than an untreated fumed silica of equal base silica surface area, the different thixotropic responses of AM-1-120 can provide better flow and leveling. 

  • Powders:

The hydrophobicity surface of KemituraSil® AM-1-120 has a lower capacity to adsorb moisture than an untreated fumed silica of equivalent base silica surface area. Therefore, KemituraSil® AM-1-120 will introduce and adsorb less moisture when used as a free-flow additive in powder systems. KemituraSil® AM-1-120 an effective free-flow additive for powder systems that are moisture sensitive. In high humidity and temperature storage conditions, powder systems incorporating KemituraSil® AM-1-120 will not have reduced caking and lumping.

For more information, please visit Ultra high-purity Silica Sol.

KemituraSil® AM-1-175 is a medium surface area fumed silica that has been surface treated with polydimethylsiloxane PDMS. This surface treatment results in hydrophobic silica with a very different performance than untreated silica.

KemituraSil® AM-1-175 provides the following advantages in the medium to high polarity systems:

  • Thickening efficiency
  • Sag resistance or high film build
  • Anti-settling of pigments and fillers
  • Shear-thinning rheological behavior
  • Stable rheological performance over time

Major Applications and Performance Features:

Typical Applications: KemituraSil® AM-1-175 is used for rheology control in a wide variety of adhesives, composite, and coatings applications.

Epoxy Adhesives and Coatings: In epoxy adhesives and coatings, KemituraSil® AM-1-175 provides good thickening efficiency, sag resistance (or film build), and anti-settling of pigments and fillers. For applications requiring storage stability, KemituraSil® AM-1-175 is recommended.

Polyurethane Adhesives and Coatings: In polyurethane adhesives and coatings

KemituraSil® AM-1-175 provides the same efficient, stable rheology control as in epoxy systems. In addition, the hydrophobic surface KemituraSil® AM-1-175 introduces very little moisture into these systems preventing premature cross-linking of moisture-cured systems.

Vinyl Ester Laminating Resins and Gel: while Untreated silica is effective thickeners of unsaturated polyester resins, KemituraSil® AM-1-175 is a more efficient, stable rheology control additive for higher polarity system like vinyl ester laminating resins and gel coats.

For more information about these or other products contact us at

Hydrophobic Fumed Silica Manufacturer

Hydrophobic FUMED SILICA

 Hydrophobic fumed silica is structure-modified silica after being treated by HMDS, PDMS, DDS and other special silanes.

HMDS treatment

Hexamethyldisilazane (HMDS) is a chemical compound that is commonly used as a surface treatment for fumed silica to make it hydrophobic. The hydrophobic treatment involving HMDS enhances the dispersibility and compatibility of fumed silica in hydrophobic systems. The HMDS molecules attach to the surface of the silica particles, creating a water-repellent coating. This modification improves the performance of fumed silica in various applications.

Hydrophobic fumed silica, treated with HMDS, is widely used in industries such as paints and coatings, adhesives and sealants, cosmetics, plastics, rubber, and composites. It is added to formulations to improve properties like rheology, thixotropic behavior, stability, moisture resistance, and flow control.

HIFULL® HB-132 (BET=140'/g)

HB-132 is Hydrophobic Fumed Silica produced by hydrophilic fumed silica with a specific surface area of 200m2/g after chemical post-treatment with HMDS (Hexamethyldisilazane). Properties Characteristics Properties Unit Typical Value Testing Standard'

HIFULL®HB-612 (BET=150'/g)

HB-612 is Hydrophobic Fumed Silica produced by hydrophilic fumed silica with a specific surface area of 150m2/g after chemical post-treatment with HMDS (Hexamethyldisilazane). Properties Characteristics Properties Unit Typical Value Testing Standard'

HIFULL® HB-615 (BET=140'/g)

HB-615 is Hydrophobic Fumed Silica produced by hydrophilic fumed silica with a specific surface area of 180m2/g after chemical post-treatment with HMDS (Hexamethyldisilazane). Properties Characteristics Properties Unit Typical Value Testing Standard'

HIFULL® HB-620 (BET=200'/g)

HB-620 is Hydrophobic Fumed Silica produced by hydrophilic fumed silica with a specific surface area of 200m2/g after chemical post-treatment with HMDS (Hexamethyldisilazane). HMDS (Hexamethyldisilazane). Properties Characteristics Properties Unit Typical Value'

HIFULL® HB-630 (BET=400'/g)

HB-630 is Hydrophobic Fumed Silica produced by hydrophilic fumed silica with a specific surface area of 400m2/g after chemical post-treatment with HMDS (Hexamethyldisilazane). Properties Characteristics Properties Unit Typical Value Testing Standard'

PDMS treatment

PDMS (Polydimethylsiloxane) hydrophobic fumed silica refers to fumed silica particles that have been surface-treated with PDMS to make them hydrophobic. When PDMS is applied to the surface of fumed silica particles, it forms a hydrophobic coating. This modification enhances the dispersibility and compatibility of fumed silica in hydrophobic systems. The PDMS molecules attach to the silica surface, creating a water-repellent layer.

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,'

DDS treatment

HIFULL® HB-151(BET=150'/g)

HIFULL® HB-151 is Hydrophobic Fumed Silica which is produced by hydrophilic fumed silica with a specific surface area of 150m2/g after chemical post-treatment with DDS(Dimethyldichlorosilane). Properties Characteristics Properties Unit Typical Value'

HIFULL®HB-152 (BET=170'/g)

HB-152 is Hydrophobic Fumed Silica which is produced by hydrophilic fumed silica with a specific surface area of 170m2/g after chemical post-treatment with DDS(Dimethyldichlorosilane). Properties Characteristics Properties Unit Typical Value Testing Standard'

special silane

HIFULL®HB-701 (BET=150'/g)

HB-701 is surface-treated fumed silica with an active silanol group modified by special silane. Properties Characteristics Properties Unit Typical Value Testing Standard Specific surface area(BET) m2/g 150±25 GB/T pH in'

HIFULL® HB-202N (BET=170'/g)

HB-202N is hydrophobic fumed silica that has been treated by a special manufacturing process to increase the polarity of the product. Properties Characteristics Properties Unit Typical Value Testing Standard Specific surface area(BET)'