Application of silica products in many industries

Silica is extremely important, one of the high-tech superfine inorganic new materials due to its small particle size, specific surface area is big, therefore the surface adsorption power, surface energy, high chemical purity, good dispersion performance, heat resistance, resistance has specific performance, with its excellent stability, reinforcing, thickening and thixotropic, and unique features in the field of the academic disciplines, having the effect that cannot replace.Silica commonly known as "ultra thin white carbon black", is widely used in various industries as additive, catalyst carrier, petrochemical industry, decoloring agent, Matting Agent, rubber reinforcing agent, plastic filling agent, ink Thickener, soft metal polishing agent, insulation insulation filler, senior daily cosmetics packing and spraying materials, medicine, environmental protection and other fields.And provides the new material foundation and the technical guarantee for the related industry domain development.Due to its magnetic, catalytic, light absorption, thermal resistance and melting point compared with conventional materials show special functions, so people pay great attention to it.

1. Electronic packaging materials

Organic electroluminescent devices (OELD) is the new development of a new type of plane display device, with opening and low driving voltage, dc voltage and can drive, can match the scale integrated circuit, easy to realize full color, high luminous intensity (> 105 CD/m2), and other advantages, but the service life of OELD device also can not meet the requirement of the application, which needs to solve the technical difficulties of packaging materials and packaging technology is one of the device.At present, the overseas (Japan, America, Europe, etc.) organic silicone modified epoxy resin, widely used by blending, copolymerization between or grafting reaction and can achieve both can reduce internal stress of epoxy resin and forming intramolecular toughening, improve the high temperature resistant performance, but also improve the organic silicon waterproof, prevent oil, antioxidant performance, but it need a longer cure time (a few hours to a few days), to speed up the curing reaction and need to be in high temperature (60 ℃ to 100 ℃ or above) or increase the use amount of Curing Agent, which not only increase the cost, but also difficult to meet the requirements of large-scale parts production line for packaging material (time is short, encapsulation) at room temperature.The curing time (2.0-2.5h) can be greatly shortened by fully dispersing the silicon dioxide treated with surface activity in the silicone modified epoxy resin packaging adhesive matrix, and the curing temperature can be reduced to room temperature, which can significantly improve the sealing performance of the OELD device and increase the service life of the OELD device.

Resin composite materials

Resin matrix composites have the characteristics of light weight, high strength, corrosion resistance, etc. But in recent years, the material industry and the pillar industry of the national economy have higher and higher requirements on the performance of resin matrix materials.The advent of silica in gas phase provides a new opportunity for the synthesis of resin matrix composites and a new way for the modification of traditional resin matrix materials.

1. Improve strength and elongation.Epoxy resin is the basic material of resin, silicon dioxide added to the epoxy resin, the structure is quite different from coarse crystal silicon dioxide (white carbon black, etc.) add epoxy resin matrix composites, coarse grain SiO2 generally as reinforcing agent, it mainly distributed in between the chains of polymer materials, and silicon dioxide due to the surface of the serious lack of coordination, large specific surface area and surface characteristics such as less oxygen, make it showed strong activity, easily and epoxy ring with molecular oxygen up key cooperation, improve the bonding force between the molecules, and at the same time there are part of the silica particles distribution in the gap in the polymer chain,Compared with coarse crystal SiO2 particles, it shows a high flow rate, which greatly improves the strength, toughness and ductility of epoxy resin added by silica.

2, improve the wear resistance and improve the material surface finish.Ultrafine silica particles are 100-1000 times smaller than ordinary silica particles.Due to the high fluidity and small size effect of silica, the surface of the material is more compact and fine, and the friction coefficient is smaller. In addition, the high strength of nanoparticles makes the wear resistance of the material greatly enhanced.

3. Anti-aging performance.A fatal weakness of epoxy resin matrix composites in the use process is poor anti-aging performance, the reason is mainly the solar radiation of 280-400nm band ultraviolet, long wave action, it is very serious damage to the resin matrix composites, polymer chain degradation led to rapid aging of resin matrix composites.However, silica can strongly reflect ultraviolet light, and adding it to epoxy resin can greatly reduce the degradation effect of ultraviolet light on epoxy resin, thus achieving the purpose of delaying material aging.

Three, plastic

The use of silica light transmission, small particle size, can make the plastic become more dense, in the polystyrene plastic film added silica, not only improve its transparency, strength, toughness, and waterproof and anti-aging performance is also significantly improved.The hardness, smoothness and anti - aging properties of plastic doors and Windows are greatly improved by adding a small amount of silica to common plastic PVC.Silica is used to analyse the common plastic polypropylene modification, the main technical indicators (water absorption, insulation resistance, residual deformation, flexural strength, compression, etc.) are reaching or higher than the performance of the engineering plastics nylon 6 indicators, implements the polypropylene railway accessories used instead of nylon 6, the product cost has fallen dramatically, it has very remarkable economic and social benefits.

Four, coating

Our country is coating production and consumption big country, but current homebred coating exists the inadequacy of performance respect generally, such as suspension stability is poor, thixotropy is poor, weather resistance is poor, be able to bear washing is poor wait, cause need to import a large number of high-quality coating every year.Shanghai, Beijing, hangzhou, ningbo and other places of some of the paint production enterprise innovation, successfully realized the application of silica in coatings, the nano modified coating change the previous product, via detecting its main performance index in addition to the contrast ratio is constant, the rest are greatly increased, such as washing resistance of exterior wall coating increased from the original one thousand times to ten thousand times, artificial accelerated weathering aging and artificial radiation exposure time from 250 hours (powder grade 1, color grade 2) up to 600 hours (without powder, paint film without color, color difference value of 4.8), in addition to coating combined with wall strength greatly increased,The hardness of the coating was increased significantly and the self-cleaning ability of the surface was also improved.

Five, the rubber

Rubber is an elastomer with excellent elasticity, but its comprehensive performance is not satisfactory. In the process of producing rubber products, carbon black is usually added into the rubber to improve the strength, abrasion resistance and aging resistance.The appearance of silica in China has laid a solid foundation for the production of new rubber products with novel colors and excellent properties.When a small amount of silica is added to ordinary rubber, the strength, abrasion resistance and aging resistance of the product reach or exceed that of high-grade rubber products, and the color can remain unchanged for a long time.Nanometer modified color epdm waterproof coil, its wear resistance, tensile strength, folding resistance, aging resistance are improved significantly, and bright color, excellent color retention effect.The development of color tires has also made some progress, such as the tire side adhesive bending performance from the original 100,000 times to more than 500,000 times, it is expected that in the near future, to achieve the color of domestic automobile, motorcycle tires.

Six, yan (dye) makings

Organic pigment (dye) materials have bright colors and strong coloring power, but the general resistance to light, heat, solvent and migration resistance is often less than inorganic pigments.By adding silica for organic pigments (dye) material for surface modification treatment, not only make yan (dye) material anti-aging performance is greatly increased, and the indicators such as brightness, hue and saturation to a certain extent, the performance can be comparable to imported high-grade products, greatly broaden the organic pigment (dye) the grade of the material and the application range.

Seven, ceramic

The addition of silica to 95 porcelain can not only play the role of nanoparticles, but also play a role of particles in the second phase, which can not only improve the strength and toughness of ceramic materials, but also improve the hardness and elastic modulus of materials, and the effect is more ideal than adding A1203.The compactness, toughness and finish of ceramic substrate were improved and the sintering temperature was decreased greatly.In addition, silica in ceramic filters, corundum ball and other ceramic products application effect is also very significant.

Eight, sealant, binder

Sealant, binder is a large amount of surface, wide range of use of important products.It requires the product viscosity, fluidity, curing speed to reach the best conditions.China's products in this field is relatively backward, high-grade sealant and binder are dependent on imports.Foreign products have been in this field using nanomaterials as modifier, and silicon dioxide is the preferred material, it mainly include apply a layer of organic material in the surface of silica, make have hydrophobic, add it to the sealant soon form a silica structure, namely the inhibition of colloidal silica particles to form network structure, to speed up the curing speed, improve the effect of bonding, because of the small silica particles', thus increasing the sealing and seepage control of the product.

Glass reinforced plastic products

Although FRP products have the advantages of light weight, high strength, corrosion resistance, but its own hardness is lower, poor wear resistance.Experts by ultrasonic dispersion method silica added to the gel coating, and without silica gel performance contrast experiment, found the mohs hardness from 2.2 (equivalent to the hardness of gypsum) increased to 2.8 ~ 2.9 (grade 3 is a natural marble hardness), 1 ~ 2 times higher wear resistance, because nanoparticles and organic polymer grafting and cooperation with key, make the material toughness increase, so the tensile strength and impact strength increased by more than 1 times, heat-resisting performance also rises sharply.

Drug carrier

With the rapid growth of municipal solid waste and the increasingly serious environmental pollution, it is urgent to intensify the efforts to eliminate the "four evils" and prevent the spread of diseases.Brush lime on the besmear on the trunk, spray liquid medicine to dustbin already effect is not big, now big city already used spray class insecticide of narcotic of central nerve kind to eliminate mosquito, fly, cockroach to wait for insect kind pest, but these insecticide import from abroad more, the price is higher, period of validity after spray is shorter (have only one month).Silica was used as the carrier to adsorb this kind of insecticide, which had a good slow release effect.

11. Cosmetics

For cosmetic, requirement is opposite ultraviolet ray screen ability is strong, had better be to be able to protect already ultraviolet medium wave (UVB) the harm to human body, also can be opposite ultraviolet long wave (UVA) have protective effect.In essence, ultraviolet shielding includes two aspects, one is the absorption of ultraviolet mentioned above, the other is the reflection of ultraviolet. At present, the anti-ultraviolet agent developed from the perspective of ultraviolet reflection performance has not been reported in the world.In sunscreen products in the past more than using organic compounds as ultraviolet absorbent, but there are such as ultraviolet light as much as possible in order to protect the skin contact and improve the content, will increase in skin cancer, and to produce the problem such as chemical allergy, and silica inorganic composition, easy compatibility with other components of cosmetics, non-toxic, tasteless, does not exist the problem, and itself is white, can simply be shaded, particularly valuable is silica reflection ultraviolet ability, good stability, is not decompose after ultraviolet irradiation, don't change color, will not react with other components in formulation.These outstanding characteristics of silica have laid a good foundation for upgrading sunscreen cosmetics.

12. Antibacterial materials

Use more mesoporous silica huge specific surface area, surface structure and strong adsorption ability and peculiar physical and chemical properties, to design the function such as silver ions equably in mesoporous silica surface, and implementation of stability, successfully developed the high efficient and durable, high temperature resistant, broad-spectrum nanometer antibacterial powder (grain size is only about 70 nanometers), not only to fill the domestic blank, and the main technical specifications are reaching or higher than Japan's similar products.According to the test, when the concentration of nano antibacterial powder in water is only 0.315%, the antibacterial ability of gram-positive and gram-negative species can be significantly revealed, and the inhibition circle is 2-3mm. Moreover, with the increase of the concentration of nano antibacterial powder in water, the inhibition circle is significantly increased.According to the determination, when the Ag content in the water is 0.01mg/1, it can completely kill the e. coli in the water, and can maintain for up to 90 days no new flora.Nanometer antibacterial powder is applied in enamel glaze to produce a roller washing machine with mildewproof and antibacterial function.It should be pointed out that the use of nano antibacterial powder in enamel glaze conditions are relatively harsh, must be in the alkaline liquid and high temperature (900℃ or so) ceramic still maintain a strong antibacterial performance, which is beyond the reach of other antibacterial powder.Nano antibacterial powder was added into the inner wall coating to produce the inner wall coating with long antibacterial and mildewproof function.Nanometer antibacterial powder was used in women's underwear detergent, wool, cashmere detergent, detergent, hand washing liquid.It is foreseeable that with the enhancement of people's health awareness, nano antibacterial powder will be gradually accepted by the general public of related application enterprises, in bills, medical health, chemical building materials, household appliances, functional fiber, plastic products and other industries emerging.

Xiii. Miscellaneous

1. Application in the optical field nano particles used in infrared reflection materials are mainly made into thin films and multi-layer films for use.Nano - particle membrane materials have a good prospect in the light bulb industry.High pressure sodium lamp and various iodine arc lamp used for taking pictures, photography requires strong illumination, but 69% of the energy after filament is heated into infrared, this suggests that there are quite a lot of electrical energy into heat energy is consumed, only a small number is converted into light energy to lighting, at the same time, the light tube heating may also affect the service life of lamps and lanterns, how to improve the luminous efficiency, increase the intensity of illumination has been a key problem presses for solution.The creation of nanoparticles provides a new way to solve this problem.Since the 1980s, researchers and technicians have made multilayer interference film with silica and nano titanium dioxide particles, with a total thickness of micron, lining the inner wall of the bulb cover, the result is not only good light transmittance, but also has a strong infrared reflection ability.According to the experts calculated that under the same light intensity, the lamp can save 15% of the electricity compared with the traditional halogen lamp.

2, the new plexiglass additive aircraft window materials commonly used is plexiglass (PMMA), when the aircraft flying at a high altitude window materials by ultraviolet radiation easy to age, resulting in a decrease in transparency.In order to solve this problem, silicon dioxide's extremely strong uv reflection performance was used to add the modified silicon dioxide in the production process of plexiglass. The product's anti-ultraviolet radiation ability was more than doubled, and the impact strength was increased by 80%.

Anticorrosion Pigments, Inkjet Receptive Coating, Matting Agent