The hydrophobic fumed silica is made by hydrolyzed chlorosilane with high temperature in hydrogen and oxygen blaze. It's an inorganic fine chemical product which is white, nonpoisonous, odorless and amorphous.
Tianyi Chemicals offers HS972, HS974 and HS976 types. It is produced by the chemical reaction of hydrophilic fumed silica and active silane (DMCS or HMDS). It presents hydrophobic properties because its surface is replaced by the unhydrolyzed methyl groups. It is white powder with high purity and cannot be dissolved in water.
The hydrophobic fumed silica is the result of combination of the chemical treatment agent and the original hydrophilic oxide with chemical bond. Besides the advantages of hydrophilic products, the hydrophobic fumed silica has low moisture absorption, great dispersion and rheological adjustment ability towards the polar system.
The hydrophobic fumed silica helps in the research and development of new products by structural modifications based on a water repellent treatment. They can also improve the product performance. When large amount of hydrophobic fumed silica is added into a liquid, the liquid viscosity changes little.
The hydrophobic fumed silica is also applied for thickening polar liquids like epoxy resins and used in a large quantity is applied to molded products. It's a good reinforcement for organosilicon elastomer and it has excellent hydrophobicity to enhance anti-corrosion properties. The hydrophobic fumed silica improves the dielectric property of cable compounds and is a good flow agent for powder used in fire extintors.
The hydrophobic fumed silica is also used to enhance scratch resistance on coating and plastics. It's packed in a 10 Kg white bag that should be stored in a dry and cool place away from sunshine.Specifications of the Hydrophobic Fumed Silica
|Specific surface m2/g||115±15||170±20||230±25||GB/T 10722|
|PH (4%) (water ethanol=1:1)||3.7-4.5||5.5-8.0||5.5-8.0||GB/T 1717|
|Loss on drying (105℃, 2h), w%||≤0.5||≤0.5||≤0.5||GB/T 5211.3|
|Loss on cauterization (1000℃, 2 hr %)||≤2.5||≤4.0||≤4.0||GB/T 20020|
|SiO2 content %||≥99.8||≥99.8||≥99.8||GB/T 20020|
|Surface density||40-60||40-60||40-60||GB/T 5211.4|
|Carbon content||0.6-1.2||1.5-2.5||2.5-4.0||GB/T 20020|