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Fumed silica - a pyrogenic silicon dioxide
Fumed silicas
Fumed silica is a highly versatile chemical that is used in a wide range of applications. Although hydrophilic by nature, it can be treated to become hydrophobic. This type of silica can be found in many kinds of products (e.g. adhesives, coatings or printing inks) and is thus very valuable to the chemical industry. As a trusted distributor and supplier to the sector, TER Chemicals is able to provide you with high quality fumed silica and other specialty chemicals.
In terms of its chemical composition, fumed silica consists mainly of high-purity, amorphous silicon dioxide (SiO2) that has aggregated into larger particles.
It also contains trace amounts of iron, phosphorous, aluminum, magnesium and calcium.
Silica, also called white carbon black, is an oxide of silicon and is synthetically produced using continuous combustion processes. In nature, it can be found in both plants and animals, such as brown algae and radiolarians. When radiolarians die and settle at the ocean floor, they form special deposits known as radiolarian ooze.
This ooze mainly comprises silica, with water and metal oxides accounting for a smaller part of its composition. Silica can also be found in groundwater because rainwater that seeps into lower layers of soil can absorb silica from the minerals there.
Fumed silica, an odorless, non-toxic and hydrophilic substance, is produced using flame hydrolysis. During the process, sand (the initial material) is reduced by carbon to create silicon, which is then converted to silicon tetrachloride through the addition of chlorine. Finally, silicon tetrachloride is combusted at high temperatures in oxyhydrogen (hence the term "fumed").
The result of fumed silica manufacturers is a loose, white powder that is non-porous and has a very low density, called fumed silica, microsilica or silica fume. One special feature of fumed silica is its exceptionally high specific surface area. This gives the compound its excellent properties: high elasticity, high strength, effective reinforcing agent, low viscosity, hydrophobic, ability to improve the pourability of powders, effective desiccant, and anti-caking ability (facilitates free-flow).
- a wide range of uses
- ability to improve a powder's pourability
- effective desiccant
- ability to prevent wetting and caking
Industries
Paints, coatings, adhesives, sealants, printing inks, etc.
Objects that are highly susceptible to corrosion caused by environmental factors can be protected using paints and coatings that contain fumed silica. Applying such coatings to a product can improve its rheological properties. Fumed silica in a specific particle size can enhance the flow properties of paints and coatings, thus reducing the likelihood of air entrapment and shrink holes when they dry. Furthermore, the compound is an anti-settling agent and can be viscosity-increasing.
When added to paints and coatings, fumed silica forms a shell around pigment particles, resulting in the stabilization of pigments and fillers. This has the following benefits:
- preventing reagglomeration
- preventing an increase in viscosity
- preventing sedimentation of pigments and fillers
In addition, pyrogenic silica can improve coating hardness (i.e. higher scratch resistance) and function as a matting agent to give products a pleasing, sleek look.
Fumed silica is also used in printing inks. It helps improve print sharpness by acting as a charge control agent. Due to their positive charge, pigment molecules are anchored very close to the paper's surface, enabling the moisture in the ink to be adsorbed in deeper layers of the paper. The result is a sharp, bold print.
As a supplier of specialty chemicals, we will be happy to answer any questions you may have regarding the use of pyrogenic silica in coatings, paints and inks.
Fumed silica can be added to adhesives and sealants to improve their rheological properties and make them more thixotropic. On top of that, it enhances the strength of adhesives and sealants, thus maximizing their stability, facilitating curing and boosting cohesive strength. The addition of fumed silica is especially beneficial to adhesives used for construction joints, sealing applications or elastic objects.
Regardless of whether it's the automotive, aerospace or construction industry - fumed silica is added as a thickener to increase the viscosity of an adhesive due to its three-dimensional structure. This makes it easier to process, mix and apply the adhesive without it dripping. Fumed silica can likewise reinforce polymers, which leads to higher cohesive strength. Therefore, silica products are able to make adhesives easier to handle and give them long-lasting stability during use and storage.
As a supplier of specialty chemicals, we will be happy to answer any questions you may have regarding the use of pyrogenic silica in adhesives and sealants.
