Characteristics and application of silica
Silica has many uses, and different products have different uses. Used as a good reinforcing agent for synthetic rubber, its reinforcing performance is second only to carbon black, and even better than carbon black if it is ultra-fine and properly surface treated. It is especially suitable for the manufacture of white, colored and light-colored rubber products. Used as thickening agent or thickening agent, blending agent for synthetic oils and insulating paints, fading agent for paint, thixotropic agent for encapsulating materials of electronic components, precipitating agent for phosphor powder when coating fluorescent screen, filling of color printing rubber plate agent, casting release agent. Adding it into the resin can improve the moisture-proof and insulating properties of the resin. Filled in plastic products to increase slip resistance and oil resistance. Filled in silicone resin, it can be made into plastic resistant to above 200℃. Used as filler and surface furnish for paper in the paper industry.

Precipitated silica is a widely used material for rubber reinforcement. Generally speaking, because the reinforcement effect of precipitated silica (except for ultra-fine and surface treatment) is not as good as that of carbon black, it is a semi-reinforced filler material. Therefore, the percentage of replacing carbon black should be determined according to the application. Precipitated silica is used in rubber products including inner and outer tires of automobiles, dumpers, trucks, tractors, forklifts, bicycles, etc., industrial belts, hoses, liners, rubber sheets, threshing rollers for grain processing, and rubber shoes. Silica is used more or less in all kinds of rubber industrial products. Adding a certain amount of silica to ordinary tires can improve the service life of tires. According to the test results of tire formulation research of a former West German company, if 10-20 parts of silica can be added, the adhesiveness and tear resistance can be improved, the tire mileage can be increased, and the tire's resistance to the road surface can be enhanced. Grip force for safe driving. The mileage of tires in my country is lower than the international level, and the absence of silica is one of the reasons. In addition, due to the high calorific value of carbon black, foreign automobile tires used for highways also tend to add silica. At present, the requirements for bicycle tires in domestic and foreign markets are also increasingly diversified. For example, new fancy varieties such as tire bead colorization and flashing circles are produced with white carbon black instead of carbon black. In the production of rubber shoes, people not only require fastness, but also beautiful color, comfortable and lightweight for rubber shoes, rain boots, sports shoes, travel shoes, fitness shoes, ballet shoes, etc. Silica not only has good reinforcement, wear resistance, slip resistance and upper adhesion, but also is a good light-colored reinforcing material. Therefore, it plays an important role in providing the quality and style of shoes in the development of rubber shoes. important role.

Silica can be used as a filler material in polyethylene, polypropylene, polybutene, epoxy resin and other plastics, which can improve the elastic strength and wear resistance of plastics, as well as the thermal stability of hardness. It can also improve the electrical insulation of cables when used in cables. For example, methyl vinyl silicone rubber high-voltage wires should use fumed silica or high-quality precipitated silica. It is often difficult to separate the two layers of plastic films, and it is difficult to open the mouth of the bag when bagging, so white carbon black is a very useful opening agent. When PVC is used as a home floor material, if a certain amount of white carbon black is added, the properties of the product such as hardness, elasticity and thermal denaturation can be improved.

Silica is used as a sizing agent for paper, which can improve the whiteness and opacity of paper, improve printability, oil resistance, abrasion resistance, hand feel and gloss. When used for printing drawings, it can make the paper surface with good quality, stable ink and no cracks on the back; when used in azide paper, it can produce high-quality blueprints; when used in coated paper, it can replace titanium dioxide; especially for newsprint, adding 1 to 2% of white carbon black can reduce the weight of the paper by 10%, not only the paper is thin, but also can improve the strength, in addition to preventing the penetration of ink and making the printed text clear, it can also increase the opacity. Silica has thixotropic properties. Adding a small amount of silica in the coating can eliminate the droplet sedimentation phenomenon in the coating. In unsaturated polyester coatings, as long as 0.5 to 2% concentration of silica is added, the coating can be applied on a vertical surface at 500g/m2 without droplets and wrinkles.

Adding white carbon black to the pigment can not only prevent the precipitation of the pigment, but also improve the adsorption of the pigment and dye, and improve the dispersibility. Improves thermal stability when used as a filler for emulsion coatings. In order to meet the requirements of coating and ink matting agents for silica, special products for matting agents have been developed and produced abroad. When nitro varnish and similar coatings contain precipitated silica matting agent, it can improve the non-precipitation properties of the paint, and make the paint easy to disperse, with only a small amount of thickening effect, good suspension, excellent matting characteristics, and high transparency. and good wear resistance. Adding 0.5% white carbon black to the printing ink, the printing effect is good, which can eliminate the influence of the penetration of the undispersed ink, improve the washing resistance of the printing material, and increase the gloss of the color.

In addition, white carbon black is also used in various degrees and plays various beneficial functions in pesticides, medicines, adhesives, toothpaste and daily cosmetics.