Application of nanometer silicon dioxide
Liu Tao (Shanghai Huijingya Nano New Material Co., Ltd.)
Nano silica is a nano material with great industrial application prospects. Its application fields are very wide, involving almost all industries that use silica powder. The research on nanomaterials in China started relatively late, until After the "Eighth Five Year Plan" listed "nanomaterials" as a major basic project, the research in this field began rapidly and achieved remarkable results. In 1996, nano silica was successfully developed and became an important member of the family of nanomaterials, making China the fifth country in the world after the United States, Britain, Japan and Germany to be able to mass produce this product. The application of nano silica is very extensive.
I In the field of coating
Nano silica has a three-dimensional network structure, has a large specific surface area, and shows great activity. It can form a network structure when the paint is dry, while increasing the strength and smoothness of the paint, and improving the suspension of the pigment, which can keep the color of the paint from fading for a long time. In the building Exterior wall coating If nano silica is added, the can opening effect of the coating can be significantly improved. The coating does not delaminate, and has good thixotropy, anti sagging, and application performance, especially the anti fouling performance is greatly improved, with excellent self-cleaning ability and adhesion. Due to the large specific surface area of nano silica particles, they can have a strong cross-linking effect with polymer molecules. At the same time, due to the small size of nano silica particles, they can fill the pores in the coating, making the coating more compact, greatly improving the shear force and peel force of the coating, and increasing the adhesion of the coating. Moreover, the addition of nano silica makes the corrosion potential of the composite paint move forward, the anodic corrosion current decreases by about 2 orders of magnitude, and the corrosion resistance of the coating is significantly improved. Nano-Si02, as a functional component, is added into the coating system to make nano modified coatings, which can improve the scrub resistance, stain resistance and other properties of the coatings, and give them special functions such as antibacterial and self-cleaning. Nano silica has special optical properties that conventional sio2 does not have. it has strong ultraviolet absorption and infrared reflection characteristics. Adding nano-sio2 to the coating can effectively reduce the color difference value of the coating caused by ultraviolet and infrared radiation, which is due to the ultraviolet radiation can affect the C - H C-C, C-C 1 and other bonds as well as substances with bond energy have destructive effects, while nano-sio2 has a high shielding rate to ultraviolet rays. Adding paint can shield ultraviolet rays, thus improving the aging resistance and weather resistance of exterior wall coatings.
two ： In the field of adhesives and sealants
In the field of adhesives and sealants, nano silica is an important product with large amount and wide application range. At present, domestic high-grade sealants and adhesives mainly rely on imports. It is reported that foreign products in this field have used nanometer materials as additives, and nanometer silicon dioxide is the preferred material. Its mechanism is that the surface of nanometer silicon dioxide is coated with organic materials to make it hydrophobic. Adding it to the sealant can quickly form a network structure, inhibit the flow of colloid, accelerate the solid speed, and improve the bonding effect, At the same time, due to the fine particles, the sealing property of the adhesive is increased.
3： Application in rubber As a reinforcing agent and anti-aging agent, nano silica can be used in rubber products to improve the strength, toughness, anti-aging, friction and ignition resistance, and prolong the service life of rubber products. In addition, it can also be used to manufacture transparent rubber soles, which used to rely on imports.
4： Application in plastics : Adding nano silica into plastics can improve the toughness, strength, abrasion resistance, anti-aging property and anti-aging property of plastics. For example, polypropylene plastics are modified with nano silica (PP) can be used to manufacture automobile bumper; Another example: after adding nano silica into the translucent plastic film, not only the transparency, toughness and strength are improved, but also the waterproof and weather resistance are greatly enhanced; For another example, the use of nano silica in PMMA can improve its strength, impact toughness, abrasion resistance, light transmittance, UV resistance and anti-aging performance ， Adding nano silica into plastics can improve the toughness, strength, wear resistance, aging resistance and aging resistance of plastics 。 Nano silica as nucleating agent, Suitable for polyethylene, polypropylene and other incomplete crystalline plastics ； It is By changing resin It is a new functional additive that can accelerate the crystallization rate, increase the crystal density and promote the micro refinement of the grain size, so as to shorten the molding cycle and improve the transparency, surface gloss, tensile strength, rigidity, thermal deformation temperature, impact resistance, creep resistance and other physical and mechanical properties of products.
V: In the field of textile
With the development of science and technology and the improvement of human living standards, people put forward the concept of comfort for clothing Requirements for novel health care All kinds of functional textiles came into being. Here, nano silica has played a huge role. At present, people have applied it to UV protection Far red antibacterial deodorant Anti aging, etc. For example, the composite powder formed by the proper ratio of nano silica and nano titanium dioxide is an important additive for anti ultraviolet radiation fibers. Another important feature of the fiber added with nano materials is that it has a strong absorption effect on the infrared ray of the human body, which can increase the warmth retention effect and reduce the weight of clothes. Clothes made of fibers added with infrared absorption nano material powder can reduce the weight About 30%.
6： In the field of antibacterial agents and catalysis
Nano silica is physiologically inert and highly adsorbable. It is often used as a carrier in the preparation of fungicides. When nano silica is used as a carrier, it can adsorb antibacterial ions to achieve antibacterial and antibacterial purposes. It can be used in the manufacture of refrigerator shells, computer keyboards, etc.
Nano-sio_2 has large specific surface area, high porosity and many surface active centers, so it has potential application value in catalyst and catalyst carrier. The composite oxides containing nano silica can be prepared by using nano silica as the basic raw material and sol-gel technology. When the composite oxide is used as catalyst support, it will show unique reaction performance for many structure sensitive reactions. The reaction has high catalytic activity, good selectivity and can maintain catalytic activity for a long time`
VII: In the field of agriculture and food
Recently, developed countries have developed some new application fields of nano silica. For example, in agriculture, using nano silica to produce agricultural seed treatment agent can make vegetables (Cabbage, tomato, yellow rice, cotton, corn and wheat can improve the yield and advance the maturity period. For example, nano silica can be used in herbicides and insecticides. If a small amount of nano silica is added to the granular formula of insecticide, it will effectively control and prevent the generation of harmful substances. In the food industry, nano silica also has many applications, such as food packaging bags with nano silica, which can keep fruits and vegetables fresh; The application of nano silica in liquor production can purify and extend the fresh-keeping period; It can also be used as a highly effective bactericide to prevent and cure various diseases of fruits and vegetables.
VIII: In the field of lubricant additives
In the field of lubricating oil additives, the surface of nano silica particles contains a large number of hydroxyl groups and unsaturated bonds, which can form a solid chemisorption film on the surface of friction pairs, protect the metal friction surface, and significantly improve the friction performance of lubricating oil. The bearing capacity of lubricating oil is greatly improved after adding nano-sio_2. When the amount of additive is 1.5, the PB value is nearly doubled. As a lubricating oil additive, nano-sio_2 particles show excellent anti-wear and antifriction properties, and play a certain role in repairing the wear surface. In the field of lubricating oil additives In the field of lubricating oil additives, the surface of nano silica particles contains a large number of hydroxyl groups and unsaturated bonds, which can form a solid chemisorption film on the surface of friction pairs, protect the metal friction surface, and significantly improve the friction performance of lubricating oil. Sio2 nanoparticles as lubricant additives show excellent anti-wear and antifriction properties, and play a certain role in repairing the wear surface.
IX Other areas
Nano silica has high surface energy and adsorption properties, good stability and biological affinity, and can be used as a new sensor; The hardness and strength of the artificial teeth can be greatly improved and the SJ property of the artificial teeth can also be improved by using the characteristics of non-toxic nano-sio2, tasteless, pollution-free, candle resistant, reinforcing and toughening. Nano silica was used in the brush plating process to improve the mechanical properties and fretting wear properties of the coating; Nano silica can be used in ink as dispersant And flow control agent; It has important applications in skin care products, electronic assembly materials, thermal insulation materials, and even can save energy and protect the environment.
