Silica is one of the extremely important new inorganic materials, especially nano-sized silica due to its small particle size, so it has a large specific surface area, strong surface adsorption, large surface energy, high chemical purity, and good dispersion performance. It has special properties in terms of thermal resistance, resistance, etc. With its superior stability, reinforcement, thickening and thixotropy, it has unique characteristics in many disciplines and fields, and has an irreplaceable role. Let's take a look at the areas in which nano-silica can be used.
1. Application in the rubber industry
Rubber is an elastomer with excellent flexibility, but its comprehensive performance is not satisfactory. It is usually necessary to add carbon black to the rubber in the process of producing rubber products to improve the strength, wear resistance and aging resistance. However, due to carbon The addition of black makes the products all black, and the grade is not high. The advent of silica in my country has laid a material foundation for the production of a new generation of rubber products with novel colors and excellent performance. After adding a small amount of silica to ordinary rubber, the strength, abrasion resistance and aging resistance of the product can reach or exceed high-grade rubber products, and the color can remain unchanged for a long time.
In the rubber industry, silica is usually used in vulcanized silicone rubber, medical rubber products, tires, hoses, tapes and daily necessities (rubber shoes, electrical appliances, and cultural and sports products).
2. Application in the plastics industry
In thermoplastics, fumed silica can improve the toughness of plastics. After it is added to plastics, it can increase the toughness of the material without weakening the rigidity of the material, and even increase the rigidity of the material.
In thermosetting plastics, adding fumed silica to epoxy resin can significantly improve its brittleness, which can overcome the defects of material rigidity and strength reduction caused by the toughening of elastomers, and achieve the purpose of strengthening and toughening.
In plastics, silica can also be used as a flame retardant. Because fumed silica increases the strength of the carbon-silicon layer through the physical process in the condensed phase, it can prevent the transfer of heat and substances during combustion.
3. Application in coatings
In light-curing coatings, nano-silica is filled into UV-curing coatings to significantly increase the hardness and heat resistance of the cured coatings. At the same time, it can improve the curing speed, hardness, adhesion and thermal stability of the UV-curable coating film.
In architectural coatings, silica can effectively reduce the color difference of the coating caused by ultraviolet and infrared light irradiation, and improve the aging resistance of exterior wall coatings. It can also significantly enhance the hardness, adhesion, and weather resistance of the coating, increase the viscosity and anti-settling ability of the coating, and enhance the stability of the coating.
In the inkjet printing paper coating, adding nano-silica to the pigment can produce a good-performance digital color inkjet printing paper special coating, which not only can make the coating load moderate, but also can effectively solve the problem of formaldehyde. The printing effect is good, the materials are easily available, and it can be said to be economical and practical.
In addition, adding silica to plastic and metal coatings can significantly improve the performance of the material.
Fourth, the application in the field of ceramics
First of all, silica is the main component of quartz ceramics. Secondly, as an additive, it can also effectively enhance the performance of ceramics. For example, using silicon dioxide instead of nano Al2O3 to add to 95 porcelain, it can not only play the role of nano particles, but also the second phase particles, which not only improves the strength and toughness of ceramic materials, but also improves the hardness and hardness of the materials. The elastic modulus and other properties are more ideal than adding Al2O3.
The use of silica to composite the ceramic substrate not only improves the density, toughness and smoothness of the substrate, but also greatly reduces the sintering temperature. In addition, the application effect of silica in ceramic products such as ceramic filters and corundum balls is also very significant.
5. Application in the field of drug carriers and catalysis
Nano-silica is physiologically inert and highly absorbent, and is often used as a carrier in the preparation of fungicides. When nano silica is used as a carrier (UG-S07AG), it can absorb antibacterial ions to achieve antibacterial purposes. It can be used in the manufacture of refrigerator shells and computer keyboards. Nano-silica has large specific surface area, high porosity and many surface active centers, and has potential application value in catalysts and catalyst supports. Using nano-silica as the basic raw material and using sol-gel technology, composite oxides containing nano-silica can be prepared. When this composite oxide is used as a catalyst support, it will show unique reaction performance for many structurally sensitive reactions. The catalytic activity of the reaction is high, the selectivity is good, and the catalytic activity can be maintained for a long time during the reaction.
6. Application in electronic packaging
The three main materials of electronic packaging are substrate materials, plastic packaging materials, lead frames and solders. Among plastic packaging materials, epoxy plastic packaging materials (EMC) are the mainstream of integrated circuit packaging at home and abroad. In EMC, the content of silicon dioxide powder accounts for 60% to 90%. In electronic packaging, high moisture resistance, low stress, low alpha radiation, resistance to dip soldering and reflow soldering, and good plastic packaging process performance are mainly required after integrated circuit packaging. In response to these requirements, the epoxy molding compound must be doped with inorganic fillers in the resin matrix. The current inorganic fillers are basically silica powder, which can reduce the thermal expansion coefficient of the molding compound, increase the thermal conductivity, and reduce the dielectric constant, which is environmentally friendly. , Flame retardant, reduce internal stress, prevent moisture absorption, increase the strength of the plastic packaging material, and reduce the cost of the packaging material.
7. Application in sealant and adhesive
Sealants and adhesives are important products with a large quantity, a wide range and a wide range of applications. It requires the best conditions for product viscosity, fluidity, and curing speed. my country's products in this field are relatively backward, and high-end sealants and adhesives rely on imports. Foreign products in this field have used nanomaterials as modifiers, and silica is the preferred material. It is mainly coated with a layer of organic material on the surface of silica to make it hydrophobic and add it to the sealant A kind of silica structure is formed soon, that is, the small silica particles form a network structure to inhibit the flow of colloids, accelerate the curing speed, and improve the bonding effect. The small size of the silica particles also increases the sealing and impermeability of the product. .
8. Application in FRP products
Although FRP products have the advantages of light weight, high strength, and corrosion resistance, they have low hardness and poor wear resistance. Relevant experts added silica to the gel coat resin by ultrasonic dispersion method, and performed performance comparison experiments with the gel coat without silica, and found that its Mohs hardness was increased from the original 2.2 (equivalent to the hardness of plaster) to 2.8~2.9 level (level 3 is the hardness of natural marble), the abrasion resistance is increased by 1~2 times, because the nano-particles and the organic polymer have grafting and bonding, which increases the toughness of the material, so the tensile strength and impact strength Increased by more than 1 time, heat resistance is also greatly improved.
9. Application in cosmetics
In the past, organic compounds were mostly used as UV absorbers in sunscreen products. However, there are problems such as increasing the amount of addition in order to protect the skin from ultraviolet rays as much as possible, which will increase the occurrence of skin cancer and chemical allergies, while silica is inorganic Ingredients, easy to be compatible with other cosmetics components, non-toxic, odorless, without the above problems, and itself is white, can be simply colored, especially valuable is that silica has strong ability to reflect ultraviolet rays, good stability, and is irradiated by ultraviolet rays It will not decompose, will not change color, and will not chemically react with other components in the formula. These outstanding features of silica have laid a good foundation for the upgrading of sunscreen cosmetics.
10. Applications in the optical field
High-pressure sodium lamps and various iodine arc lamps used for photography and photography require strong lighting, but 69% of the energy of the filament is converted into infrared rays, which indicates that a considerable amount of electrical energy is converted into heat and is consumed, only a little Part of it is converted into light energy for lighting. At the same time, the heating of the lamp tube will also affect the life of the lamp. How to improve the luminous efficiency and increase the illumination has always been a key issue to be solved urgently. Since the 1980s, scientific researchers have used silicon dioxide and nano-titanium dioxide particles to make a multilayer interference film with a total thickness of micrometers, lining the inner wall of the bulb cover. The result is not only good light transmittance, but also strong infrared reflection. ability. According to experts' calculations, this type of lamp can save 15% of electricity compared with traditional halogen lamps under the same brightness.
11. Application in the textile field
With the development of science and technology and the improvement of human living standards, people have put forward comfortable, novel and health-care requirements for clothing, and various functional textiles have emerged. Here, nano-silica plays a huge role. At present, people have applied it to anti-ultraviolet, far-red antibacterial deodorization, anti-aging and other aspects. The fiber added with nanomaterials has another important feature, that is, it has a strong absorption effect on human body infrared, which can increase the warmth retention effect and reduce the weight of clothes. Clothes made of fibers added with infrared-absorbing nanomaterial powder can weigh Reduced by about 30%.
12. Application in agriculture and food
In recent years, developed countries have developed some new applications of nano-silica. For example, in agriculture, the use of nano-silica as an agricultural seed treatment agent can increase the yield of vegetables (cabbage, tomatoes, yellow, cotton, corn, wheat, etc.) and mature earlier. For example, nano-silica can be used in herbicides and insecticides. If a small amount of nano-silica is added to the granular insecticidal thorn formulation, it will effectively control and prevent harmful substances. In the food industry, nano-silica also has many applications, such as food packaging bags added with nano-silica, which can preserve the freshness of fruits and vegetables; the application of nano-silica in wine production can purify and extend the preservation period It can also be used as a high-efficiency fungicide for preventing and curing various diseases of fruits and vegetables.
13. Application in the field of lubrication
Silica can also be used as a lubricant, an excellent flow promoter, mainly as a lubricant, anti-sticking agent, and glidant. It is especially suitable for the granulation of oils and medicinal extracts. The prepared granules have good fluidity and compressibility. It can also be used as a glidant in direct compression. As a disintegrant, it can greatly improve the fluidity of the particles, increase the bulk density, increase the hardness of the prepared tablets, shorten the disintegration time limit, and increase the dissolution rate of the drug. It can be used as an internal desiccant in the manufacture of granules to enhance the stability of the drug. It can also be used as filter aid, clarifying agent, defoaming agent, suspending agent and thickening agent for liquid preparations.
14. Application in papermaking
In the paper industry, fumed silica products can be used as a paper sizing agent, can improve the whiteness and opacity of paper, and can improve oil resistance, abrasion resistance, feel, printability, and gloss. It can also be used for printing paper, which can make the surface of the paper good, the ink is stable, and there is no crack on the back. It can also be used in azide paper to produce excellent blue drawings, which can be used in copper paper to replace titanium dioxide.
Adding 1-2% fumed silica product can reduce the weight of the paper, and the paper is thin, can improve the strength, prevent ink penetration, can also make the printed text clear and increase the opacity.