fumed silica ss380 CAS NO.112945-52-5

Hydrophilic fumed silica

Product name: SS^®380

CAS NO 112945-52-5

SYNONYMS: fumed silicon dioxide

Physical Description:

Fumed Silica is composed of submicron-sized spheres, which are 40-60% fused into short chains, very highly branched,0.1-0.2microns long. The spheres are quite uniform in size for a given product, but the chain lengths are quite variable,10 to 30 units in length. The surface area, which varies with the particle size, gives a good approximation if the sphere diameter. The smaller the particles, the larger the estimated surface area.

SS® 380  is a hydrophilic fumed Silica with specific surface area of 150m2/g, and it synthetic, hydrophilic, amorphous silica, produced via flame hydrolysis. Particle between 7～40nm.

Along with the traditional polyester, silicone, paints and coatings applications, hydrophilic SS® 380  products are used with increasing success in high technology fields. The particle nature and high purity of fumed silica play key roles in the electronics and optical fibers industries.

Physical-chemical Data

METHOD OF PREPARATION:

Silicon tetrachloride is burned in a flame of hydrogen and oxygen(at approximately 1800℃) to produce molten spheres of silicon dioxide(and hydrogen chloride). Depending on process parameters, the size of these silica spheres can be varied and, in a given batch, show excellent uniformity(by electron micrograph). The molten spheres collide and fuse with one another to form branched, three-dimensional chain-like aggregates.

Many aggregates have chains from 10 to 30 spheres in length, or from0.1 to 0.2 microns(um) in length. As the aggregates cool down below the fusion temperature of silica(approximately 1710℃),further collisions result in some reversible mechanical entanglement or agglomeration. Further agglomeration occurs during the collection process; this can be reversed by proper dispersion in a suitable medium.

During the formation of the product, hydroxyl groups become attached to some of the silicon atoms on the surface of silica particles, making the surface hydrophilic and capable of hydrogen bonding with suitable molecules. There are (estimated)3.5-4.5 hydroxyl groups per square millimicron of silica surface, compared to a theoretical maximum of 7.85. The structure of fumed silica is amorphous (as indicated by absence of lines in its X-ray diffracetion pattern.)

The surface area was determined by calculation using a nitrogen adsorption method of brunauer,and the value used to calculate particle diameter.

The residual hydrogen chloride on the surface of the fumed silica was reduced to less than 200ppm by calcining. The moisture content of the product will vary,depending on storage conditions. moisture adsorbed on the surface can be removed by evacuation at room temperature (at 10^-2mm Hg) or by heating at 110℃,(if the product is heated above 800℃,it sinters irreversibly.)

SOLUBILITY /SOLUTION STABILITY:

Fumed silica will form dispersions in water, glycerine, butyl alcohol, mineral oil and a variety of other liquids, causing them to thicken or form gels. The dispersions often have thixotropic properties, i.e, viscosity that varies with rate of stirring.

For liquids with minimal hydrogen bonding, small amounts of fumed silica will increase the viscosity. Addition from 3 to5% by weight usually suffices to cause the liquid to form a gel. After an initial thorough dispersion, increasing the mixing time has little effect on the viscosity for a given percent of silica.

For liquids with a high degree of hydrogen bonding, small amounts of fumed silica will also increase the viscosity. However, usually 10% or more (by weight) will be needed form gels.The initial dispersion is rapid. If the dispersion is mixed too long, the result will be an irreversible decrease in viscosity.

Furthermore, the hydrophilic SS^® grades are characterized by an X-ray amorphous structure. Depending on the market and application, products with various primary particle sizes and different BET-surface areas are available.

Application:

◇As thixotropic and thickening agent of liquid ,  anti-settling, anti-sagging .

◇Improve the suspension and dispersion of pigment in liquid system .

◇Be used as dispersing and grinding aids

◇To improve anti-corrosion of coating
◇Improve powder fluidity and storage stability

◇To improve powder charge and charge stability.
◇To improve water proof
◇To improve scratch resistance of painting surface
◇To improve the brightness of color
◇To fix special effect
◇To improve the physical and mechanical properties of paint film

◇To improve adhesion and flexibility of paint film
◇To improve the rubber, elastomer viscoelastic, reinforcing
◇Anti bubble effect in the anti foaming agent
◇To improve the hardness and anti scratch of coating
◇To prevent adhesion in film and elastomer
◇Use as Adsorbent and carrier
◇Be used in ink painting
◇Be used as high level filler of teeth material
◇As a catalyst carrier, significant thermal insulation is used for both  low and high  temperature insulation

Positive effects:

   1 Rheology control:

Optimum adjustment of rheology during processing

Rheology control of greases and lubricants

Sag resistance

Anti-settling

Thickening of non-polar liquids

Free-flow of foodstuffs and industrial powders

Gelification of battery acids

2 Mechanical enhancement

Reinforcement of silicone elastomers

Scratch resistance

Hardness and anti scratch of coating film

3 Anti-corrosion

High chemical purity

Excellent insulation properties, even at high temperatures

Conversion of liquids to powders, e.g. pharmaceuticals, cosmetics

   Anti-blistering, Reduced scribe creep

Packing and storage

SS^®380is packed in multiple layer kraft paper 10kg bags on pallet, and should be stored in the original packaging in dry storage areas for protecting the material from volatile substance.

Special requirements on packaging can be negotiated with the company.   

Transportation

Sea transportation

20’ GP : 1800KG, 10 pallets, 180KG/pallet

40’ GP : 3600KG, 20 pallets, 180KG/pallet

40’ HQ : 4000KG,20 pallets, 200KG/pallet

Road transportation: by request