Use Fumed Silica as Anti-sedimentation Agents
The World Bank expects global economic growth to slow significantly, from 5.5% in 2021 to 4.1% in 2022 and further to 3.2% in 2023. Growth in East Asia and the Pacific is expected to slow to 5.1 percent in 2022, reflecting the impact of China's economic slowdown, the report said. China's economic growth is expected to fall to 5.1% in 2022, close to potential growth, due to the ongoing impact of the COVID-19 pandemic and the Chinese government's tightening of regulations in certain sectors of the economy. The report said that the rapid spread of the Omicron variant means that the new crown epidemic is likely to continue to disrupt economic activity in the near future. In addition, decelerating growth in major economies, including the United States and China, will depress external demand in emerging markets and developing economies.
Slow economic growth has a huge impact on fumed silica.
Fumed silica is a kind of inorganic nanomaterial with a small particle size, large specific surface area, and high surface activity.
It is mainly used as a rheological auxiliary agent in paint and coating, which can effectively prevent flow hanging and thick edges in the construction process and improve construction efficiency.
In addition, silica in the coating is also used as an anti-sedimentation and dispersant aid, can effectively prevent the sedimentation of the pigment delamination, improve the coating weather resistance, scratch resistance, and the bonding strength between the coating and the substrate.
Fumed silica is an ideal anti-sedimentation agent, its hydrogen bond structure is very stable and uniform, and it is a three-dimensional network structure, which is very effective to prevent the precipitation of pigment in the coating system. Especially for the color paste system, the appropriate amount will greatly improve the stability of color paste, and can reduce the amount of wetting dispersant, to improve the applicability of color paste and reduce the influence of color paste on the coating system. At the same time, the anti-sedimentation effect of fumed silica is very beneficial to the storage of coatings, especially some pigments such as metal powder and thin sections, which are easy to precipitate and cannot be completely suspended, the use of fumed silica can ensure that its dispersion does not precipitate.
The precipitation of fumed silica is very beneficial for coating storage and transportation. For some pigments, such as metal powder and thin film, it is easy to precipitate and cannot be effectively suspended. The use of fumed silica can ensure that the mixture is uniform and does not cause sedimentation. In absolute non-polar liquid phase, such as hydrocarbons (hydrocarbons) without hydrogen bond (chemical structure such as R-H) bonding ability, halogenated hydrocarbon (halogen and hydrocarbon electrophilic addition or substitution reaction) solvent, the viscosity recovery time is only a fraction of a second; Thixotropic recovery in polar liquids, such as hydrogen-bonded amines (R-NH3), alcohols (R-OH), carboxylic acids (R-COOH), aldehydes (R-CHO), and dialcohols (such as Ho-Rh2-OH, where R- is a saturated alkyl group), can take up to several months, depending on the amount of fumed silica added and the uniformity of mixing. The fumed silica is pre-dispersed and added to the finished paint. Usually, a high-speed dispersing machine or three-roller machine is used to improve the dispersion effect. If the dispersion is not good, the paint film will have particles, affecting gloss and aesthetics.
In addition, as an anti-sedimentation agent, fumed silica is added to coppery acrylic resin conductive coating. The test proves that it can make the thermoplastic acrylic resin thixotropic and prevent the deposition of filler particles, but if the addition amount is too much, the coating becomes a gel state, the conductivity of the coating would be reduced.
In the powder system, because of the small particle size and high surface energy, silica can be adsorbed on the surface of the coating powder, and form a surface layer on the surface of the powder to improve the dispersion of the powder. In the same coating system, the addition of fumed silica can obviously shorten the dispersion time and improve the production efficiency.
The addition of fumed silica in wall coating can effectively prevent coating from hanging, improve the flatness of the construction surface, and also greatly improve the washing resistance and aging time of exterior wall coating. The bonding strength of coating film and the wall is also greatly improved, the hardness of coating film is significantly increased, and the surface self-cleaning ability is also improved.
The adsorption of fumed silica on the surface of powder coating can form a movable layer and produce a "ball bearing" effect, which can prevent the powder coating from absorbing moisture and agglomerating and improve the fluidity of powder coating.
The main function of floor paint is the rheological control, improving the weatherability and scratch-resistance of floor paint, and improving the leveling performance of the coating.
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Recently, Russia's deputy prime minister said that the number of countries buying Russian oil is increasing, including Asian countries. Russia will use the "East Siberia-Pacific" pipeline system to increase exports to Asian countries and promote the diversification of oil output.
He also said that Russian oil fumed silica are expected to continue to increase in the future.