Calcium carbonate is an inorganic compound with the chemical formula CaCO ₃, commonly known as limestone, limestone, stone powder, marble, etc. Calcium carbonate is neutral, basically insoluble in water, soluble in hydrochloric acid. It is one of the common substances on the earth. It exists in rocks such as aragonite, calcite, chalk, limestone, marble and tufa. It is also the main component of animal skeleton or shell. Calcium carbonate is also an important building material, widely used in industry. According to the crystal structure, it can be divided into the following three types: ① aragonite type. It is orthorhombic white crystal. ② Calcite type . Hexagonal white crystal. It is insoluble in water, but soluble in acid and ammonium chloride, also soluble in water containing carbon dioxide.
1、Application in rubber industry
Calcium carbonate is one of the most widely used fillers in rubber industry. The rubber industry is also one of the main application markets of nano calcium carbonate, which can be used in rubber products such as tires, rubber tubes, tapes, sealing rings, automobile accessories, etc. Nano CaCO3 has the properties of ordinary calcium carbonate first, and because of its ultra-purity, ultrafine and surface modification characteristics, it has three-dimensional space structure and good dispersion in the rubber, which can improve the tensile properties, reinforcement properties and anti-aging properties of the materials. It can not only be used as reinforcement filler alone, but also combined with other fillers (silica, carbon black, light or heavy calcium carbonate, titanium dioxide, clay, etc.) to fill, reinforce and color match, improve product performance and processing technology, reduce the glue content or partially replace expensive white fillers such as titanium dioxide and silica, and reduce costs. Nano calcium carbonate used in rubber industry requires small particle size, high surface activity and good dispersion. The effect of nano calcium carbonate on the surface oxidation of SBS rubber can be studied by compounding nano calcium carbonate with SBS rubber after UV surface treatment.
2、Application in plastics industry
At present, the most mature industry of nano calcium carbonate application technology is the plastic industry, and the demand for calcium carbonate in the plastic industry is also very large. Due to its unique excellent properties, nano calcium carbonate can be used as a modifier, reinforcing agent and semi reinforcing agent for plastics. The nano calcium carbonate has small particle size and good dispersion, which can reduce the pores and voids in the plastics, and make the mixing and shrinkage of the plastics more uniform. Therefore, it can be filled in the polymers of polystyrene, polyvinyl chloride, aldehyde, phenol plastics, etc., so as to improve the dimensional stability, hardness and rigidity of plastic products. At the same time, because of its lipophilic and hydrophobic properties, the activated nano calcium carbonate can greatly improve the toughness, rigidity, bending strength and finish of the products, improve its heat resistance, dimensional stability and other processing properties, and partly replace other expensive fillers and additives, thus reducing the production cost of products and improving the market competitiveness.
3、Application in paper industry
The use of nano calcium carbonate in paper industry has the following advantages: 1) the whiteness and light shielding properties of paper products have been significantly improved; 2) the wear of nano calcium carbonate on paper is smaller, so that the paper products can be more uniform and smoother. 3) Reduce the amount of pulp, increase the amount of filler, reduce the production cost; 4) Nano calcium carbonate has good oil absorption, which can improve the pigment firmness of color paper; 5) nano calcium carbonate can improve the tightness of neutral paper or paperboard. At present, nano calcium carbonate is mainly used in printing paper, recording paper, high whiteness coated paper, cigarette paper, diapers and high-grade sanitary napkins. Nano calcium carbonate can also improve the apparent fineness, bulk density and water resistance of paper, improve the printing speed and strength of special paper, and adjust the burning speed of cigarette paper.
4、Application in coating industry
Nano calcium carbonate as pigment filler is the most potential market. At present, the amount of calcium carbonate in coating industry is increasing rapidly. Calcium carbonate has many advantages in coating industry, such as fine, uniform, high whiteness and good optical performance. When added in water-borne coatings, it can greatly improve the reinforcement, transparency, thixotropy and leveling of the system, and obviously improve the stain resistance, brush resistance, adhesion and anti-sedimentation effect of the coating. The application of nano calcium carbonate in exterior wall coating can improve its pollution resistance and crack resistance because of its strong hydrophobicity. Nano calcium carbonate can replace high price titanium dioxide, reduce the amount of other additives, and significantly reduce the production cost of coatings.
5、Application of ink in industry
Nano calcium carbonate and good printing performance. Due to the small particles, so the print is smooth, dot integrity, strong covering power. Nano calcium carbonate as filler can improve the brightness and gloss of ink. In the process of ink printing, it can also show good ink absorption, which helps to improve the fast drying performance of the ink. Nano calcium carbonate as the filler of ink, in addition to the role of ordinary ink filler, but also has good stability, high gloss, strong adaptability, does not affect the drying characteristics of ink and other advantages, and low price, can reduce costs. Nano calcium carbonate used in high-grade ink can improve the adhesion of ink, reduce the mechanical wear of ink, suitable for high-speed printing.