Talc powder is made by grinding natural talc ore after peeling off the iron oxide on the surface. The main component is magnesium silicate. Talc is a phyllosilicate and hydrous magnesium silicate mineral. There are few natural pure talc mines, and most of them are associated with other mineral impurities. The standard associated minerals are chlorite, serpentine, magnesite, tremolite, and dolomite. Talc is usually white, light green, slightly pink, or light gray; the more impurities it contains, the darker the color, even dark gray or black. In the monoclinic crystal system, the ore is often in the form of flakes, fibers, and dense blocks, pearly or grease luster. When talc is heated, it has an apparent thermal effect. It loses adsorbed water at 120-200 degrees Celsius and begins to lose part of the structural water at 600 degrees Celsius until all the structural water reaches 1050 degrees Celsius. X-ray diffraction or differential thermal analysis is the best way to identify talc. Talc is widely distributed in the crustal lithosphere, and its origin is related to regional metamorphism and hydrothermal exchange.
Talc powder is a hexagonal or rhombic plate-shaped crystal sheet structure density of 2.7, a hardness of 1, and a greasy feeling. It is mainly used in putty and coating industries to improve workability and fluidity. In addition, due to the lamellar structure, the coating film can effectively absorb the stress caused by expansion or contraction, avoid cracks in the coating film, and increase its strength of the coating film.
Talc powder can also improve the construction performance of coatings so that it can widely use talc powder in various coatings. Because talc powder is soft and easy to absorb moisture, it must be combined with other pigments and fillers when preparing putty and paint. The interior and exterior wall putty is formulated with talc powder, and the glue has poor weather and water resistance and can easily cause chalking.
However, due to the different quality of talc ore, its associated mineral composition is different, and the processing technology is also other so that talc powder can be divided into several varieties. Coatings are generally used for coating grade talcum powder, and fine talc powder should be used for high-grade coatings. The talc powder used for coatings should contain as few impurities as possible. Adding a small talc powder to architectural waterproof coatings can prevent pigment precipitation and coating sagging. And it can absorb stretching stress in the coating film to avoid and reduce cracks and voids.
Limestone powder
Limestone powder is a mixed active filler, mainly composed of calcium oxide, calcium hydroxide, and a small amount of calcium carbonate mixed in a particular proportion. Its primary raw material is CaCO3, such as calcite and marble, which becomes calcium oxide after high-temperature flint firing by selecting, carbonizing, partially digesting, and then crushing, grounding, and screening.
Limestone powder is mainly used in interior and exterior wall putty and paint. It will undergo a chemical and cross-linking reaction to a certain extent during the drying process to improve wear resistance, hiding power, and scrub resistance of paint. Lime calcium powder can replace slaked lime and quicklime in dry-mixed mortar products.
