Application of fumed silica (2)


7, ceramic
The use of fumed silica instead of nano-A1203 added to 95-ceramic can act as both a nanoparticle and a second-phase particle, which not only improves the strength and toughness of the ceramic material, but also increases the hardness and elasticity of the material. Modulus and other properties, the effect is more ideal than adding A1203. The composite ceramic substrate is made of fumed silica, which not only improves the compactness, toughness and smoothness of the substrate, but also greatly reduces the sintering temperature. In addition, the use of fumed silica in ceramic filters, corundum balls and other ceramic products is also very significant.

8, sealant, adhesive
Sealant and adhesive are important products with large quantity, wide surface and wide application range. It requires optimum viscosity, fluidity, and cure speed. China's products in this field are relatively backward, and high-grade sealants and adhesives are imported. Foreign products in this field have used nano-materials as modifiers, and fumed silica is the preferred material. It is mainly coated with an organic material on the surface of fumed silica to make it hydrophobic. Add it to A silica structure is formed quickly in the sealant, that is, the nano-Si0X small particles form a network structure to inhibit the colloidal flow, accelerate the curing speed, and improve the bonding effect. The gas-phase white carbon black particles have a small ruler and thus increase the sealing and prevention of the product. Permeability.

9, glass steel products
Although the FRP products have the advantages of light weight, high strength and corrosion resistance, they have low hardness and poor wear resistance. The relevant experts added the fumed silica to the gel coat resin by ultrasonic dispersion method, and compared with the gel coat without the addition of fumed silica, the Mohs hardness was found to be 2.2 grade (corresponding to the hardness of gypsum). Increased to 2.8 ~ 2.9 (3 is the hardness of natural marble), wear resistance increased by 1 to 2 times, due to the grafting and bonding of nanoparticles and organic polymers, so that the toughness of the material increases, so tensile strength and resistance The impact strength is increased by more than one time, and the heat resistance is also greatly improved.

10, drug carrier
With the rapid growth of urban domestic garbage and the increasing environmental pollution, it is urgent to increase the intensity of eliminating the "four evils" and prevent the spread of diseases. It is not very effective to apply lime on the trunk and spray the syrup to the garbage can. Nowadays, large cities have used spraying central nervous anesthetic insecticides to eliminate insect pests such as mosquitoes, flies and cockroaches, but these insecticides are mostly Imported from abroad, the price is higher, and the effective period after spraying is shorter (only one month). The gas-phase white carbon black is used as a carrier to adsorb the insecticide, which has a good sustained-release effect. According to the measurement, the effective period after spraying is more than one year.

11, cosmetics
For cosmetics, it is required to have strong UV shielding ability. It is best to protect against UVB damage to the human body and to protect against UVA. In essence, the ultraviolet shielding includes two aspects, one is the absorption of ultraviolet rays as described above, and the other is the reflection of ultraviolet rays. At present, the anti-ultraviolet agent developed from the viewpoint of ultraviolet reflection performance in the world has not been reported. In the sunscreen products, organic compounds have been frequently used as ultraviolet absorbers. However, in order to protect the skin from ultraviolet rays as much as possible, the amount of skin cancer and chemical allergy may increase, and the gas phase white carbon black is Inorganic component, easy to be distributed with other groups of cosmetics, non-toxic, odorless, does not have the above problems, and is white in itself, can be easily colored, especially expensive gas black silica has strong UV reflectivity and good stability. It does not decompose after UV irradiation, does not change color, and does not react chemically with other components in the formulation. These outstanding features of fumed silica have laid a good foundation for the upgrading of sunscreen cosmetics.

12, antibacterial materials
Using the large specific surface area of the gas phase silica, the surface multi-mesoporous structure, the superabsorbent ability and the singular physicochemical properties, functional ions such as silver ions are uniformly designed into the mesopores of the surface of the fumed silica and stabilized. Successfully developed high-efficiency, long-lasting, high-temperature resistant, broad-spectrum antibacterial nano antibacterial powder (particle size is only about 70 nanometers), which not only fills the domestic gap, but also the main technical indicators have reached or exceeded similar products in Japan. After testing, when the concentration of nano antibacterial powder in water is only 0.315%, the antibacterial ability of Gram-positive representative strains and Gram-negative representative strains can be clearly revealed, and the inhibition zone appears 2— 3mm, and with the increase of the concentration of nano antibacterial powder in water, the inhibition zone increased significantly. It has been determined that when the water contains Ag+ of 0.01 mg/1, it can completely kill E. coli in water and maintain a new flora for up to 90 days. The nano antibacterial powder is applied to the enamel glaze to produce a drum washing machine with mildewproof and antibacterial functions, and the antibacterial rate is as high as 99% or more. It should be pointed out that the nano antibacterial powder is used in enamel glazes in harsh conditions. It must maintain strong antibacterial properties after burning in a highly alkaline liquid and high temperature (about 900 ° C). This is another antibacterial powder. Unpredictable. The nano antibacterial powder is added to the interior wall paint to produce an interior wall paint with long-lasting antibacterial and mildew resistance. The nano antibacterial powder is used in women's underwear detergent, wool, cashmere detergent, detergent, hand soap, and the antibacterial performance is very significant after being tested by the health and epidemic prevention department. It can be foreseen that with the enhancement of people's health awareness, nano antibacterial powder will gradually be accepted by the general public of relevant application enterprises, and it will emerge in the industries of bills, medical and health, chemical building materials, home appliances, functional fibers and plastic products.