Yuan Lei's Little Knowledge | Talcum Powder Indicators in Plastics Industry
The main component of talc is talc water-containing magnesium silicate, molecular formula Mg3[Si4O10](OH)2. Talc is monoclinic. The crystals are false hexagonal or rhombohedral flakes. Usually dense massive, leaf-like, radial, fibrous aggregates. Colorless transparent or white, but with a small amount of impurities and light green, light yellow, light brown or even light red; cleavage surface was pearl luster.
Talc can be used as a filler for a variety of plastics. As a plastic filler, talc can not only save the amount of resin used, but also improve the rigidity, impact strength, creep resistance, hardness, surface scratch resistance, heat resistance and heat distortion temperature of the product. The index requirements of talc powder for plastics mainly include purity, whiteness, flake degree, fineness, SiO2 content, fluidity, static electricity, etc.
Purity refers to the content of talc powder, talc in nature and industrial production contains impurities, 100% of pure talc products in industry is impossible to exist. Therefore, the higher the purity of the talc, the better the reinforcing effect. Some impurities in talcum powder will not only reduce the purity, but also lead to the deterioration of the aging resistance and thermal stability of plastic products.
Although the level of whiteness has no effect on the physical properties of the product, it is very important to maintain the purity of the color for light-colored products. One disadvantage of talcum powder is that the color of the plastic becomes more or less dark after mixing, which is An important factor that limits the wide application of talc in plastics.
But in fact, in many applications do not need to use white talc, in dark plastic, the use of high or low whiteness of talc is no difference.
The significant reinforcing effect of talc on plastic products only comes from its unique micro-sheet structure. The more complete the flake structure of talcum powder, the more obvious the strengthening effect. The two main factors that affect the flake of the product are: talc clarity, powder processing essentials and skills.
Micronization is the development trend of talc products. The finer the product, the better the enhancement effect, but at the same time, the surface energy of the particles increases, it is easy to reunite, it is difficult to disperse, and the price is also high. Therefore, it is necessary to choose the appropriate fineness of the product according to its own technical level and actual needs, not necessarily the finer the better.
5. SiO2 content
The silicon content in talc powder is an important index to measure the quality of talc powder. Therefore, it is necessary to choose talcum powder according to different performance requirements of plastic products. For example, the silicon content of talcum powder added in the film should be higher, the particle size is small and the particle size distribution is narrow, so that the light transmittance, tensile strength, puncture resistance and other indicators of the film can be significantly improved. In the injection molding, plate, bar silicon content requirements do not have to be too high, low silicon content of talcum powder price is low, while rich in resources.
In the extrusion process, talc has poorer fluidity than other granular inorganic materials, is difficult to disperse, and has a large screw torque. Therefore, the use of better activation additives is the key to overcome the above problems.
7. static electricity
Talc has a layered structure with a large specific surface area. The irregularity of particle shape and the convex and concave shape of the surface make its friction coefficient large and easy to generate static electricity, resulting in condensation between tiny particles, which is difficult to disperse and affects the application effect. Static storage to eliminate static technology, both simple and practical, and easy to operate.
Plastic, talc, talc, product, content, flake, purity, electrostatic, effect
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Kaolin is a non-metallic mineral, which is a kind of clay and clay rock mainly composed of kaolinite clay minerals. Because it is white and delicate, also known as white earth. It is named after Gaoling Village, Jingdezhen, Jiangxi Province.