Application of active calcium carbonate

1, in the plastic can improve the stability of the size of plastic products, hardness and steel, improve the processing performance of plastic and the heat resistance and astigmatism of its products;
2, as a filler in rubber, it can increase the volume, reduce the cost, improve the processing performance and vulcanization performance;
3, in papermaking can be used as paper filler, white pigment of coated paper, calcium plastic paper filler, etc.
4. As a filler in the paint, it can play a skeleton role, so it is called "constitutional pigment"; In oil-based coatings, the filling amount can reach 10-50%, and in water-based coatings, the filling amount can reach 10-20%. Active calcium carbonate is used as the base material, and the surface of inorganic powder is modified and activated by using multi-functional surfactants and compound high efficiency processing AIDS. The modified calcium carbonate powder forms a special coating structure on its surface, which can significantly improve the dispersibility and affinity in polymer matrix such as polyolefin, and can produce interfacial interaction with polymer matrix, so as to improve the impact strength of the product. It is a kind of incremental filling agent with excellent performance. The filling amount is generally 30-100%, and some products are even more than 100 copies.

Characteristics of active calcium carbonate
(1) Appearance: white powder, tasteless, non-irritating, non-combustible, non-explosive, low refraction rate, easy to color, insoluble in water, stable in air.
(2) After the activation of the product, the molecular structure changes, the particle size distribution is uniform, and the product is extremely hydrophobic.
(3) It has the characteristics of high whiteness, good fluidity, good gloss, uniform dispersion, large filling amount, etc. It has excellent lubricity, fluidity, dispersion and organicity.
(4) The molecular affinity with rubber and plastic is strong, the filling amount can be filled 2-5 times to several times more than ordinary calcium carbonate, and the comprehensive production cost is significantly reduced.
(5) Low oil absorption value, high whiteness, high elongation, and its unique super metal stripping and significant lubrication effect can also improve the brightness of the surface of the product, wear and impact strength.
(6) It can reduce the wear of processing machinery, improve product processing technology, improve product performance, and have a good reinforcing effect.
(7) The product is used in advanced coatings, which can improve the solid filling amount and reduce viscosity, while giving the coating wear resistance, corrosion resistance, reduce baking temperature, shorten baking time, improve product quality, reduce production costs, and have obvious economic benefits.

Production technology of active calcium carbonate
The production process of active calcium carbonate is roughly the same as that of light calcium carbonate, but the conditions should be strictly controlled in the carbonization process to generate fine calcium carbonate particles, and then the surface treatment with activator. The mixture of limestone and coal, the ratio of about 7.5, is burned in the lime kiln at the temperature of 900-1000℃. The carbon dioxide is sent to the carbonization tower after the dust removal by washing gas, and the quick lime is fed into the digestion tank and fully digested with 80-90℃ hot water to make the emulsion with a concentration of about 9%, which enters the carbonization tower and carbonizes with carbon dioxide. When the PH value of the suspension is equal to 7 during carbonization, it is the reaction end point. At this time, activators can be introduced to surface treatment of the generated calcium carbonate.

Surface treatment methods include dry surface treatment and wet surface treatment, usually using wet surface treatment process. Active calcium carbonate with high activation, good dispersion and high transparency can be prepared by this method. At present, the active agent is generally added phthalic acid coupling agent, stearic acid, lignin, etc., the amount is about 1%-5%. After the previous chemical treatment is completed, the material liquid is dehydrated, separated, and dried to produce the finished product with high whiteness. Factories producing general light calcium carbonate only need to improve some equipment and processes, such as improving the reaction tower, increasing temperature control, gas flow and surface modification, etc., to produce qualified active calcium carbonate products and improve the added value of products.