Silica is a generic term for white powdered X-ray amorphous silicic acid and silicate products, mainly precipitated silica, fumed silica and ultrafine silica gels, but also powdered synthetic aluminium silicate and calcium silicate. Silica is a porous substance, the composition of which can be expressed as SiO2-nH2O, where nH2O is in the form of surface hydroxyl groups. It is soluble in caustic soda and hydrofluoric acid, insoluble in water, solvents and acids (except hydrofluoric acid). It is high temperature resistant, non-flammable, tasteless, odourless and has good electrical insulation.

Basic information

Main applications

The following are the applications of fumed silica in various industries

Electronic Packaging Materials

Organic electroluminescent device (OELD) is a new type of flat display device newly developed at present. It has low turn-on and driving voltage, and can be driven by DC voltage. High (>105cd/㎡) and other advantages, but the service life of OELD devices can not meet the application requirements, one of the technical difficulties that need to be solved is the packaging material and packaging technology of the device. At present, silicone-modified epoxy resins are widely used in foreign countries (Japan, the United States, Europe, etc.), that is, through the blending, copolymerization or grafting reaction between the two, it can not only reduce the internal stress of epoxy resin but also form molecules. Internal toughening improves the high temperature resistance, and also improves the waterproof, oil-proof, and oxygen-resistant properties of silicone, but it requires a long curing time (several hours to several days). To speed up the curing reaction, a higher Temperature (60°C to above 100°C) or increase the amount of curing agent used, which not only increases the cost, but also makes it difficult to meet the requirements of large-scale device production lines for packaging materials (short time, room temperature packaging). Fully dispersing the surface-active treated fumed silica in the silicone-modified epoxy resin packaging adhesive matrix can greatly shorten the curing time of the packaging material (2.0-2.5h), and the curing temperature can be lowered to room temperature , so that the sealing performance of the OELD device is significantly improved, and the service life of the OELD device is increased.

resin composite material

Resin-based composite materials have the characteristics of light weight, high strength, and corrosion resistance. However, in recent years, the material industry and the pillar industries of the national economy have increasingly high requirements for the performance of resin-based materials. How to synthesize high-performance resin-based composite materials has become a Important current topics in the materials and business world. The advent of fumed silica provides new opportunities for the synthesis of resin-based composite materials and a new way for the modification of traditional resin-based materials, as long as the fumed silica particles can be fully and uniformly dispersed in the resin Among the materials, the purpose of improving the properties of resin-based materials can be fully achieved.

1. Improve strength and elongation. Epoxy resin is the basic resin material. Adding fumed silica to epoxy resin is completely different in structure from epoxy resin-based composite materials added by coarse crystalline silica (white carbon black, etc.), coarse crystalline SiO2 It is generally added as a reinforcing agent, and it is mainly distributed in the chains of polymer materials, while fumed silica exhibits extremely strong properties due to its severe lack of coordination on the surface, large specific surface area, and lack of oxygen on the surface. Active, it is easy to bond with the oxygen of epoxy ring molecules, which improves the bond force between molecules. In comparison, it shows a high flow rate, so that the strength, toughness and ductility of the epoxy resin material added with fumed silica are greatly improved.

2. Improve the wear resistance and improve the surface finish of the material. Fumed silica particles are 100-1000 times smaller than SiO2, adding it to epoxy resin is beneficial for drawing into filaments. Due to the high fluidity and small size effect of fumed silica, the surface of the material is denser and finer, and the friction coefficient becomes smaller. In addition, the high strength of nanoparticles greatly enhances the wear resistance of the material.

3. Anti-aging properties. A fatal weakness in the use of epoxy resin-based composite materials is poor anti-aging performance. The reason is mainly due to the ultraviolet medium and long-wave effects of solar radiation in the 280-400nm band, which has a very serious destructive effect on resin-based composite materials. , the degradation of polymer chains leads to rapid aging of resin-based composites. Fumed silica can strongly reflect ultraviolet rays, and adding it to epoxy resin can greatly reduce the degradation effect of ultraviolet rays on epoxy resin, thereby achieving the purpose of delaying the aging of materials.

plastic

The light transmission and small particle size of fumed silica can make the plastic more dense. After adding fumed silica to polystyrene plastic film, it not only improves its transparency, strength and toughness, but also improves its waterproof performance and anti-aging performance. Significantly improved. The hardness, smoothness and aging resistance of plastic-steel doors and windows produced by adding a small amount of fumed white carbon black to ordinary plastic polyvinyl chloride