Basic Information:

        Silica is a general term for white powdered X-ray amorphous silicic acid and silicate products. It mainly refers to precipitated silica, fumed silica and ultrafine silica gel, as well as powdered synthetic silicic acid. Aluminum and calcium silicate, etc., whose main component is silica, is commonly known as white carbon black because of its reinforcing effect on rubber. White carbon black is white powdery granular or massive, non-combustible, non-toxic and tasteless, has good physiological inertia, insoluble in water, solvent and acid, but soluble in strong alkali and hydrofluoric acid, good chemical stability . The structure and application properties of silica are similar to those of carbon black. The Appearance of carbon black is black, while the Appearance of white carbon is white, which is customarily called white carbon black.

        Chinese alias: white carbon black (combustion method); gas phase white carbon black; granulated white carbon black; pharmaceutical grade white carbon black; GH-7 type white carbon black; GH-1A type white carbon black; GH-1B type white Carbon black; hydrated silica; white carbon black; white smoke; precipitated hydrated silica; pure latex; colloidal silica; precipitated silica.

Physical and chemical properties

        Appearance: white powder or granular or irregular agglomerates.

        True density: about 2.0 g/ml of false density: about 0.2 g/ml (common product).

        High temperature resistance, no burning; good electrical insulation.

        Insoluble in water, acid and solvent, but can be dissolved in hydrofluoric acid and alkali, chemical stability 
Classification

        The silica is classified into a fumed silica and a precipitated silica according to the production method. The gas phase method is mainly a chemical vapor deposition (CAV) method, which is also called a pyrolysis method, a dry method or a combustion method, and the raw materials thereof are generally silicon tetrachloride, oxygen (or air) and hydrogen, and are formed by reacting at a high temperature. The precipitation method is also called sodium silicate acidification method, and the water glass solution is reacted with an acid to obtain white carbon black by precipitation, filtration, washing, drying and calcination, which is a manufacturing method adopted by most domestic enterprises.

Uses

Precipitation method for silica

        1 Rubber industry white carbon black as a reinforcing agent, used in the rubber field, because of its strong adhesion, tear resistance and heat and aging resistance; can be used as a cement for natural rubber or synthetic rubber In the adhesive, the carbon black is replaced to greatly improve the physical properties of the rubber, enhance the thixotropic and reinforcing properties, and improve the rubber quality, such as the production of off-road tires, engineering tires, and radial tires.

        2. As an anti-caking agent, white carbon black as an anti-caking agent in agricultural chemicals, it can improve the fluidity in the product. For example, it is used for spraying fertilizer, and its ultra-high surface area has extremely high adsorption force. Easy to suspend, good affinity and chemical stability, even in rain, rinse and hot conditions, can remain unchanged for a long time.

        3. Daily chemical white carbon black is used as filler and abrasive for transparent colored and opaque toothpaste. This kind of toothpaste has good flexibility and dispersibility. The paste is smooth, soft and abrasive, and it does not abrade the toothpaste tube. And can maintain the stability of the drug toothpaste.

        4. Paper filler The white carbon black paper filler can improve the ink penetration resistance and mechanical strength, increase the whiteness and reduce the unit weight. It can effectively achieve paper weight reduction, reduce production costs, and improve paper performance.

It can also be used in many industries such as fire-fighting agents, feeds, cosmetics, matting agents, pigments, and paints.

Application of fumed silica

        Gas-phase white carbon black is one of the most important high-tech ultra-fine inorganic new materials. Because of its small particle size, it has large specific surface area, strong surface adsorption, large surface energy, high chemical purity, good dispersion performance, thermal resistance, It has specific properties in terms of electrical resistance, etc. Its superior stability, reinforcement, thickening and thixotropic properties are unique in many disciplines and fields and have an irreplaceable role. Gas phase white carbon black is commonly known as "nano white carbon black" and is widely used in various industries as an additive, catalyst carrier, decolorizing agent, matting agent, rubber reinforcing agent, plastic filler, ink thickener, metal soft polishing agent, Insulation insulation filler, advanced daily cosmetic filler and spray materials, medicine, environmental protection and other fields. It also provides new material foundation and technical guarantee for the development of related industrial fields. Since it exhibits a specific function in comparison with conventional materials in terms of magnetic properties, catalytic properties, light absorption, thermal resistance and melting point, it has received great attention. The following are the applications of fumed silica in various industries.

        1. The electronic packaging material fully disperses the surface-treated gas phase white carbon black in the silicone modified epoxy resin encapsulant matrix, which can greatly shorten the curing time of the packaging material (2.0-2.5h) and cure The temperature can be lowered to room temperature, which significantly improves the sealing performance of the OELD device and increases the service life of the OELD device.

       2. Resin composite material The meteorological white carbon black particles are fully and uniformly dispersed into the resin material to achieve the purpose of comprehensively improving the performance of the resin-based material, and a high-performance resin-based composite material is obtained.

       1Improving strength and elongation Epoxy resin is the basic resin material. Adding fumed silica to epoxy resin can greatly improve the strength, toughness and ductility of epoxy resin materials. 2 Improve wear resistance and Improve the surface finish of the material; 3 anti-aging properties, the fumed silica can strongly reflect the ultraviolet light, adding to the epoxy resin can greatly reduce the degradation of the epoxy resin by ultraviolet rays, thereby achieving the purpose of delaying the aging of the material.

        3. Plastic uses gas-phase white carbon black light transmission and small particle size. Adding fumed silica to polystyrene plastic film can make plastic more dense, improve its transparency, strength and toughness, waterproof performance and anti-aging. The performance is also obviously improved; the hardness, smoothness and anti-aging properties of plastic steel doors and windows produced by adding a small amount of fumed silica in ordinary plastic polyvinyl chloride are greatly improved; the ordinary plastic polypropylene is modified by gas phase white carbon black. The main technical indicators (water absorption rate, insulation resistance, compression residual deformation, flexural strength, etc.) all meet or exceed the performance index of engineering plastic nylon 6, and the use of polypropylene railway fittings instead of nylon 6 is realized, and the product cost is greatly reduced.

        4. Coatings used meteorological white carbon black in coatings, changing the deficiencies of previous products, scrubbing resistance, artificial accelerated weathering and artificial radiation exposure aging time were greatly improved, and the bonding strength between the coating film and the wall and the hardness of the coating film were also Significantly improved, the surface self-cleaning ability has also been improved.

        5. Rubber After adding a small amount of fumed silica to ordinary rubber, the strength, wear resistance and aging resistance of the product meet or exceed the high-grade rubber products, and the color can be kept unchanged for a long time.

        6. The pigment (dye) is modified by adding fumed silica to the organic pigment or dye to improve the anti-aging performance, and the brightness, hue and saturation are also improved to some extent. Greatly broaden the grade and application range of organic pigments.

        7. Ceramic vapor white silica instead of nano A1203 is added to 95 porcelain, which can play the role of nano particles, and it is the second phase particles, which can improve the hardness, strength, toughness and elastic modulus of ceramic materials. Performance; the use of fumed silica to composite ceramic substrates not only improves the compactness, toughness and smoothness of the substrate, but also greatly reduces the sintering temperature; the application of fumed silica in ceramic filters, corundum balls and other ceramic products Very significant.

        8. Sealant and binder Apply a layer of organic material on the surface of the fumed silica to make it hydrophobic. Adding it to the sealant quickly forms a silica structure, that is, nano-SiOX small particles form a network structure. It inhibits the flow of colloid, accelerates the curing speed, and improves the bonding effect. The smallness of the gas-phase silica black particles also increases the sealing and anti-seepage properties of the product.

        9. FRP products Adding fumed silica to the gel coat resin, the hardness and wear resistance are relatively improved, the toughness, tensile strength and impact resistance of the material are also significantly enhanced, and the heat resistance is also greatly improved.

        10. Drug Carriers Currently, large cities use imported central nervous anesthetic insecticides to eliminate insect pests such as mosquitoes, flies, and cockroaches, but they have the disadvantages of high price and short effective period after spraying. The black carrier adsorbs the insecticide, which can achieve a good sustained release effect, and the effective period after spraying is more than one year.

        11. Cosmetic fumed silica is an inorganic component, easy to be distributed with other groups of cosmetics, non-toxic, odorless, and white in itself, which can be easily colored. Especially valuable is that fumed silica has strong UV reflectivity and stability. Well, it will not decompose after being exposed to ultraviolet rays, will not change color, and will not react with other components in the formula.

        12. Antibacterial material Utilizes the large specific surface area, multi-porous structure and superabsorbent ability of the gas-phase silica, and the singular physicochemical properties, the functional ions such as silver ions are uniformly designed into the mesopores of the surface of the fumed silica. And implemented stability, successfully developed high-efficiency, long-lasting, high-temperature, broad-spectrum antibacterial nano antibacterial powder. The nano antibacterial powder is applied to the enamel glaze to produce a drum washing machine with anti-mildew and antibacterial function, and the antibacterial rate is up to 99%; the nano antibacterial powder is added to the inner wall paint to produce long-term antibacterial and anti-mildew function. The interior wall coating; the nano antibacterial powder is used in women's underwear detergent, wool, cashmere detergent, detergent, hand soap, its antibacterial performance is very significant; nano antibacterial powder is applied in enamel glaze, in alkaline Strong liquid medium and high temperature (about 900 ° C) can still maintain strong antibacterial properties after burning porcelain.