Classification characteristics and selection method of rubber filler!
Filler is one of the main raw materials in the rubber industry and is a powder material. The amount of filler is quite large, almost equivalent to the amount of rubber itself. Rubber containing fillers is a multiphase material. Fillers give rubber many valuable properties. For example, greatly improve the mechanical properties of rubber, so that the rubber has magnetic, electrical conductivity, flame retardant, color and other special properties, so that the rubber has good processing performance, reduce costs and so on.
What is reinforcement and filling?
Reinforcement: After adding a substance to the rubber, the abrasion resistance, tear strength, tensile strength, modulus, swelling resistance and other properties of the vulcanizate are greatly improved. Any substance with this effect is called reinforcing agent.
Filling: After adding a substance to the rubber, it can increase the volume of the rubber, reduce the cost of the rubber products, and improve the processing performance without significantly affecting the performance of the rubber products. Any substance with this ability is called a filler. The most commonly used fillers are mainly inorganic fillers. Such as clay, calcium carbonate, talcum powder, silicon aluminum carbon black and so on.
Carbon black is the most important reinforcing filler in the rubber industry. It is no exaggeration to say that there would be no modern rubber industry without carbon black. Carbon black consumption accounts for about half of the rubber consumption.
Of course, for a certain kind of filler is often a combination of two functions, one of which is the main role, such as clay added to SBR, mainly filling, but also has a certain reinforcing effect.
Many inorganic fillers are mainly derived from minerals, the price is low, and their application range is more and more extensive. In the rubber industry they are used almost to the same extent as carbon black. In particular, the recent research and application of inorganic filler surface modification technology has made the application field of inorganic filler more extensive.
The rubber industry is used to refer to the reinforcing effect of carbon black as reinforcing agent, and the inorganic filler with no reinforcing effect is called filler, which is classified according to the function. Fillers are classified by different methods as follows:
Method of selecting filler
According to the above three principles, the first choice of major categories. For example, it is necessary to decide whether to use powder filler or short fiber. Use black or light color; Use general or special properties, etc.
Next choose the variety. For example, in the red natural rubber tube in the choice of filler, because to make red, so the choice of white filler, cheap CaCO3 is better. Because the inner tube strength can not be too low, special requirements for air tightness. Therefore, it cannot be used too coarse, and light CaCO3 should be used.
Examples of packing performance characteristics
1, reinforcing filler: carbon black and white carbon black with large specific surface area are reinforcing, such as N110, N121, N231, N234, N347, N356, M358, N375, VN3, etc.
Semi reinforced filler: N539, N630, N683, N787, etc.
2, reduce the cost of fillers: natural minerals or by the processing of waste fillers, such as clay, calcium carbonate, silicon aluminum carbon black, fly ash and so on.
Classification of calcium carbonate
One is heavy calcium
Heavy calcium carbonate produced by mechanical crushing of calcium carbonate minerals (marble, limestone, shells, etc.). This calcium carbonate is generally larger in particle size, with an average of 44 μm or less. The particle size distribution is wide and the particle shape is irregular.
The other is light calcium
Light calcium carbonate produced by chemical methods. Because the specific preparation method is to generate calcium carbonate precipitation through CO2 in lime milk. Therefore, it is also called precipitated calcium carbonate. This calcium carbonate has a small particle size, an average particle size of several microns or less, and a narrower particle size distribution than heavy ones.
3. Fillers with special functions: Sb2O3, A1(OH)3,Mg(OH)2, MoO3, Fe2O3, etc. are flame retardant. Conductive carbon black, N472, N293 and other conductive carbon black and metal powder, etc. ZnO, Fe2O3, etc. are used to improve heat resistance. It is best to use TiO2 for whitening, BaSO4, silicon lime, etc. The best transparency is MgCO3, ZnCO3 and transparent silica.